Method for transmitting uplink control information and apparatus therefor

ABSTRACT

A method for transmitting uplink control information and an apparatus therefor are disclosed. In a method for transmitting uplink control information using a physical uplink shared channel (PUSCH) in a wireless communication system, the method is performed by a terminal and includes receiving downlink control information including an accumulated number of physical downlink shared channels (PDSCH) transmissions associated with a cell group configured for the terminal, coding the uplink control information using the accumulated number of PDSCH transmissions, and transmitting the coded uplink control information using the PUSCH.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/317,302, filed on May 11, 2021, which is a continuation of U.S.patent application Ser. No. 16/704,785, filed on Dec. 5, 2019, now U.S.Pat. No. 11,032,052, which is a continuation of U.S. patent applicationSer. No. 15/545,240, filed on Jul. 20, 2017, now U.S. Pat. No.10,523,397, which is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2016/000593, filed on Jan. 20, 2016,which claims the benefit of U.S. Provisional Application Nos.62/105,224, filed on Jan. 20, 2015, 62/115,164, filed on Feb. 12, 2015,62/144,982, filed on Apr. 9, 2015, 62/209,314, filed on Aug. 24, 2015,and 62/216,348, filed on Sep. 9, 2015, the contents of which are allhereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a wireless communication system and,more particularly, to a method for transmitting uplink controlinformation and an apparatus therefor.

BACKGROUND ART

Recently, various devices requiring machine-to-machine (M2M)communication and high data transfer rate, such as smartphones or tabletpersonal computers (PCs), have appeared and come into widespread use.This has rapidly increased the quantity of data which needs to beprocessed in a cellular network. In order to satisfy such rapidlyincreasing data throughput, recently, carrier aggregation (CA)technology which efficiently uses more frequency bands, cognitive ratiotechnology, multiple antenna (MIMO) technology for increasing datacapacity in a restricted frequency, multiple-base-station cooperativetechnology, etc. have been highlighted. In addition, communicationenvironments have evolved such that the density of accessible nodes isincreased in the vicinity of a user equipment (UE). Here, the nodeincludes one or more antennas and refers to a fixed point capable oftransmitting/receiving radio frequency (RF) signals to/from the userequipment (UE). A communication system including high-density nodes mayprovide a communication service of higher performance to the UE bycooperation between nodes.

A multi-node coordinated communication scheme in which a plurality ofnodes communicates with a user equipment (UE) using the sametime-frequency resources has much higher data throughput than legacycommunication scheme in which each node operates as an independent basestation (BS) to communicate with the UE without cooperation.

A multi-node system performs coordinated communication using a pluralityof nodes, each of which operates as a base station or an access point,an antenna, an antenna group, a remote radio head (RRH), and a remoteradio unit (RRU). Unlike the conventional centralized antenna system inwhich antennas are concentrated at a base station (BS), nodes are spacedapart from each other by a predetermined distance or more in themulti-node system. The nodes can be managed by one or more base stationsor base station controllers which control operations of the nodes orschedule data transmitted/received through the nodes. Each node isconnected to a base station or a base station controller which managesthe node through a cable or a dedicated line.

The multi-node system can be considered as a kind of Multiple InputMultiple Output (MIMO) system since dispersed nodes can communicate witha single UE or multiple UEs by simultaneously transmitting/receivingdifferent data streams. However, since the multi-node system transmitssignals using the dispersed nodes, a transmission area covered by eachantenna is reduced compared to antennas included in the conventionalcentralized antenna system. Accordingly, transmit power required foreach antenna to transmit a signal in the multi-node system can bereduced compared to the conventional centralized antenna system usingMIMO. In addition, a transmission distance between an antenna and a UEis reduced to decrease in pathloss and enable rapid data transmission inthe multi-node system. This can improve transmission capacity and powerefficiency of a cellular system and meet communication performancehaving relatively uniform quality regardless of UE locations in a cell.Further, the multi-node system reduces signal loss generated duringtransmission since base station(s) or base station controller(s)connected to a plurality of nodes transmit/receive data in cooperationwith each other. When nodes spaced apart by over a predetermineddistance perform coordinated communication with a UE, correlation andinterference between antennas are reduced. Therefore, a high signal tointerference-plus-noise ratio (SINR) can be obtained according to themulti-node coordinated communication scheme.

Owing to the above-mentioned advantages of the multi-node system, themulti-node system is used with or replaces the conventional centralizedantenna system to become a new foundation of cellular communication inorder to reduce base station cost and backhaul network maintenance costwhile extending service coverage and improving channel capacity and SINRin next-generation mobile communication systems.

DISCLOSURE OF INVENTION Technical Problem

An object of the present invention is to provide a method fortransmitting uplink control information, for more efficient channelstate reporting and proper scheduling according to channel statereporting.

Technical objects that can be achieved through the present invention arenot limited to what has been particularly described hereinabove andother technical objects not described herein will be more clearlyunderstood by persons skilled in the art from the following detaileddescription.

Solution to Problem

According to an embodiment of the present invention, provided herein isa method for transmitting uplink control information using a physicaluplink shared channel (PUSCH) in a wireless communication system. Themethod is performed by a terminal configured with more than 5 downlinkcells and includes receiving downlink control information including anaccumulated number of physical downlink shared channels (PDSCH)transmissions associated with a cell group, including one or moredownlink cells, configured for the terminal; coding the uplink controlinformation using the accumulated number of PDSCH transmissions; andtransmitting the coded uplink control information using the PUSCH.

Additionally or alternatively, the accumulated number of PDSCHtransmissions may be accumulated up to when the downlink controlinformation has been received.

Additionally or alternatively, the accumulated number of PDSCHtransmissions may be accumulated in a time-first manner.

Additionally or alternatively, the receiving, coding, and transmittingmay be performed per cell group.

Additionally or alternatively, the downlink control information may bereceived in a terminal-specific search space.

Additionally or alternatively, the uplink control information mayinclude a hybrid automatic repeat request (HARQ) acknowledgement (ACK).

Additionally or alternatively, the PUSCH includes an uplink resource percell group.

According to an embodiment of the present invention, provided herein isa terminal configured to transmit uplink control information using aphysical uplink shared channel (PUSCH) in a wireless communicationsystem, the terminal configured with more than 5 downlink cells,including a radio frequency (RF) unit and a processor configured tocontrol the RF unit, wherein the processor is configured to receivedownlink control information including an accumulated number of physicaldownlink shared channels (PDSCH) transmissions associated with a cellgroup, including one or more downlink cells, configured for theterminal, code the uplink control information using the accumulatednumber of PDSCH transmissions, and transmit the coded uplink controlinformation using the PUSCH.

The above technical solutions are merely some parts of the embodimentsof the present invention and various embodiments into which thetechnical features of the present invention are incorporated can bederived and understood by persons skilled in the art from the followingdetailed description of the present invention.

Advantageous Effects of Invention

According to an embodiment of the present invention, uplink controlinformation can be efficiently transmitted.

The effects that can be achieved through the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood bypersons skilled in the art from the following detailed description.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

FIG. 1 illustrates an exemplary radio frame used in a wirelesscommunication system.

FIG. 2 illustrates an exemplary DL/UL slot structure in a wirelesscommunication system.

FIG. 3 illustrates an exemplary DL subframe structure used in a 3GPPLTE/LTE-A system.

FIG. 4 illustrates an exemplary UL subframe structure used in a 3GPPLTE/LTE-A system.

FIG. 5 illustrates a link structure between DL and UL.

FIG. 6 illustrates an operation related to a DAI.

FIG. 7 illustrates an example of resource mapping of UCI.

FIG. 8 illustrates a logical resource region for UCI according to anembodiment of the present invention.

FIG. 9 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 10 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 11 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 12 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 13 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 14 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 15 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 16 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 17 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 18 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 19 illustrates exemplary UCI resource allocation for each CGaccording to an embodiment of the present invention.

FIG. 20 illustrates a DCI format according to an embodiment of thepresent invention.

FIG. 21 illustrates a DCI format according to an embodiment of thepresent invention.

FIG. 22 illustrates exemplary UCI resource mapping per physical uplinkshared control channel (PUSCH) according to an embodiment of the presentinvention.

FIG. 23 is a block diagram of a device for implementing embodiment(s) ofthe present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The accompanying drawings illustrate exemplary embodiments ofthe present invention and provide a more detailed description of thepresent invention. However, the scope of the present invention shouldnot be limited thereto.

In some cases, to prevent the concept of the present invention frombeing ambiguous, structures and apparatuses of the known art will beomitted, or will be shown in the form of a block diagram based on mainfunctions of each structure and apparatus. Also, wherever possible, thesame reference numbers will be used throughout the drawings and thespecification to refer to the same or like parts.

In the present invention, a user equipment (UE) is fixed or mobile. TheUE is a device that transmits and receives user data and/or controlinformation by communicating with a base station (BS). The term ‘UE’ maybe replaced with ‘terminal equipment’, ‘Mobile Station (MS)’, ‘MobileTerminal (MT)’, ‘User Terminal (UT)’, ‘Subscriber Station (SS)’,‘wireless device’, ‘Personal Digital Assistant (PDA)’, ‘wireless modem’,‘handheld device’, etc. A BS is typically a fixed station thatcommunicates with a UE and/or another BS. The BS exchanges data andcontrol information with a UE and another BS. The term ‘BS’ may bereplaced with ‘Advanced Base Station (ABS)’, ‘Node B’, ‘evolved-Node B(eNB)’, ‘Base Transceiver System (BTS)’, ‘Access Point (AP)’,‘Processing Server (PS)’, etc. In the following description, BS iscommonly called eNB.

In the present invention, a node refers to a fixed point capable oftransmitting/receiving a radio signal to/from a UE by communication withthe UE. Various eNBs can be used as nodes. For example, a node can be aBS, NB, eNB, pico-cell eNB (PeNB), home eNB (HeNB), relay, repeater,etc. Furthermore, a node may not be an eNB. For example, a node can be aradio remote head (RRH) or a radio remote unit (RRU). The RRH and RRUhave power levels lower than that of the eNB. Since the RRH or RRU(referred to as RRH/RRU hereinafter) is connected to an eNB through adedicated line such as an optical cable in general, cooperativecommunication according to RRH/RRU and eNB can be smoothly performedcompared to cooperative communication according to eNBs connectedthrough a wireless link. At least one antenna is installed per node. Anantenna may refer to an antenna port, a virtual antenna or an antennagroup. A node may also be called a point. Unlink a conventionalcentralized antenna system (CAS) (i.e. single node system) in whichantennas are concentrated in an eNB and controlled an eNB controller,plural nodes are spaced apart at a predetermined distance or longer in amulti-node system. The plural nodes can be managed by one or more eNBsor eNB controllers that control operations of the nodes or schedule datato be transmitted/received through the nodes. Each node may be connectedto an eNB or eNB controller managing the corresponding node via a cableor a dedicated line. In the multi-node system, the same cell identity(ID) or different cell IDs may be used for signal transmission/receptionthrough plural nodes. When plural nodes have the same cell ID, each ofthe plural nodes operates as an antenna group of a cell. If nodes havedifferent cell IDs in the multi-node system, the multi-node system canbe regarded as a multi-cell (e.g., macro-cell/femto-cell/pico-cell)system. When multiple cells respectively configured by plural nodes areoverlaid according to coverage, a network configured by multiple cellsis called a multi-tier network. The cell ID of the RRH/RRU may beidentical to or different from the cell ID of an eNB. When the RRH/RRUand eNB use different cell IDs, both the RRH/RRU and eNB operate asindependent eNBs.

In a multi-node system according to the present invention, which will bedescribed below, one or more eNBs or eNB controllers connected to pluralnodes can control the plural nodes such that signals are simultaneouslytransmitted to or received from a UE through some or all nodes. Whilethere is a difference between multi-node systems according to the natureof each node and implementation form of each node, multi-node systemsare discriminated from single node systems (e.g. CAS, conventional MIMOsystems, conventional relay systems, conventional repeater systems,etc.) since a plurality of nodes provides communication services to a UEin a predetermined time-frequency resource. Accordingly, embodiments ofthe present invention with respect to a method of performing coordinateddata transmission using some or all nodes can be applied to varioustypes of multi-node systems. For example, a node refers to an antennagroup spaced apart from another node by a predetermined distance ormore, in general. However, embodiments of the present invention, whichwill be described below, can even be applied to a case in which a noderefers to an arbitrary antenna group irrespective of node interval. Inthe case of an eNB including an X-pole (cross polarized) antenna, forexample, the embodiments of the preset invention are applicable on theassumption that the eNB controls a node composed of an H-pole antennaand a V-pole antenna.

A communication scheme through which signals are transmitted/receivedvia plural transmit (Tx)/receive (Rx) nodes, signals aretransmitted/received via at least one node selected from plural Tx/Rxnodes, or a node transmitting a downlink signal is discriminated from anode transmitting an uplink signal is called multi-eNB MIMO or CoMP(Coordinated Multi-Point Tx/Rx). Coordinated transmission schemes fromamong CoMP communication schemes can be categorized into JP (JointProcessing) and scheduling coordination. The former may be divided intoJT (Joint Transmission)/JR (Joint Reception) and DPS (Dynamic PointSelection) and the latter may be divided into CS (CoordinatedScheduling) and CB (Coordinated Beamforming). DPS may be called DCS(Dynamic Cell Selection). When JP is performed, more variouscommunication environments can be generated, compared to other CoMPschemes. JT refers to a communication scheme by which plural nodestransmit the same stream to a UE and JR refers to a communication schemeby which plural nodes receive the same stream from the UE. The UE/eNBcombine signals received from the plural nodes to restore the stream. Inthe case of JT/JR, signal transmission reliability can be improvedaccording to transmit diversity since the same stream is transmittedfrom/to plural nodes. DPS refers to a communication scheme by which asignal is transmitted/received through a node selected from plural nodesaccording to a specific rule. In the case of DPS, signal transmissionreliability can be improved because a node having a good channel statebetween the node and a UE is selected as a communication node.

In the present invention, a cell refers to a specific geographical areain which one or more nodes provide communication services. Accordingly,communication with a specific cell may mean communication with an eNB ora node providing communication services to the specific cell. Adownlink/uplink signal of a specific cell refers to a downlink/uplinksignal from/to an eNB or a node providing communication services to thespecific cell. A cell providing uplink/downlink communication servicesto a UE is called a serving cell. Furthermore, channel status/quality ofa specific cell refers to channel status/quality of a channel or acommunication link generated between an eNB or a node providingcommunication services to the specific cell and a UE. In 3GPP LTE-Asystems, a UE can measure downlink channel state from a specific nodeusing one or more CSI-RSs (Channel State Information Reference Signals)transmitted through antenna port(s) of the specific node on a CSI-RSresource allocated to the specific node. In general, neighboring nodestransmit CSI-RS resources on orthogonal CSI-RS resources. When CSI-RSresources are orthogonal, this means that the CSI-RS resources havedifferent subframe configurations and/or CSI-RS sequences which specifysubframes to which CSI-RSs are allocated according to CSI-RS resourceconfigurations, subframe offsets and transmission periods, etc. whichspecify symbols and subcarriers carrying the CSI RSs.

In the present invention, PDCCH (Physical Downlink ControlChannel)/PCFICH (Physical Control Format Indicator Channel)/PHICH(Physical Hybrid automatic repeat request Indicator Channel)/PDSCH(Physical Downlink Shared Channel) refer to a set of time-frequencyresources or resource elements respectively carrying DCI (DownlinkControl Information)/CFI (Control Format Indicator)/downlink ACK/NACK(Acknowledgement/Negative ACK)/downlink data. In addition, PUCCH(Physical Uplink Control Channel)/PUSCH (Physical Uplink SharedChannel)/PRACH (Physical Random Access Channel) refer to sets oftime-frequency resources or resource elements respectively carrying UCI(Uplink Control Information)/uplink data/random access signals. In thepresent invention, a time-frequency resource or a resource element (RE),which is allocated to or belongs toPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH, is referred to as aPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH RE orPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resource. In the followingdescription, transmission of PUCCH/PUSCH/PRACH by a UE is equivalent totransmission of uplink control information/uplink data/random accesssignal through or on PUCCH/PUSCH/PRACH. Furthermore, transmission ofPDCCH/PCFICH/PHICH/PDSCH by an eNB is equivalent to transmission ofdownlink data/control information through or onPDCCH/PCFICH/PHICH/PDSCH.

FIG. 1 illustrates an exemplary radio frame structure used in a wirelesscommunication system. FIG. 1(a) illustrates a frame structure forfrequency division duplex (FDD) used in 3GPP LTE/LTE-A and FIG. 1(b)illustrates a frame structure for time division duplex (TDD) used in3GPP LTE/LTE-A.

Referring to FIG. 1 , a radio frame used in 3GPP LTE/LTE-A has a lengthof 10 ms (307200 Ts) and includes 10 subframes in equal size. The 10subframes in the radio frame may be numbered. Here, Ts denotes samplingtime and is represented as Ts=1/(2048*15 kHz). Each subframe has alength of 1 ms and includes two slots. 20 slots in the radio frame canbe sequentially numbered from 0 to 19. Each slot has a length of 0.5 ms.A time for transmitting a subframe is defined as a transmission timeinterval (TTI). Time resources can be discriminated by a radio framenumber (or radio frame index), subframe number (or subframe index) and aslot number (or slot index).

The radio frame can be configured differently according to duplex mode.Downlink transmission is discriminated from uplink transmission byfrequency in FDD mode, and thus the radio frame includes only one of adownlink subframe and an uplink subframe in a specific frequency band.In TDD mode, downlink transmission is discriminated from uplinktransmission by time, and thus the radio frame includes both a downlinksubframe and an uplink subframe in a specific frequency band.

Table 1 shows DL-UL configurations of subframes in a radio frame in theTDD mode.

TABLE 1 Downlink- DL-UL to-Uplink config- Switch-point Subframe numberuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U 1 5ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms D S U U U D DD D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D D D D 6 5 ms D SU U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes threefields of DwPTS (Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS(Uplink Pilot TimeSlot). DwPTS is a period reserved for downlinktransmission and UpPTS is a period reserved for uplink transmission.Table 2 shows special subframe configuration.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Special subframe Normal cyclic Extended cyclicNormal cyclic Extended cyclic configuration DwPTS prefix in uplinkprefix in uplink DwPTS prefix in uplink prefix in uplink 0  6592 · T_(s)2192 · T_(s)  2560 · T_(s)  7680 · T_(s) 2192 · T_(s)  2560 · T_(s) 119760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) *5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) *5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — —9 13168 · T_(s) — — —

FIG. 2 illustrates an exemplary downlink/uplink slot structure in awireless communication system. Particularly, FIG. 2 illustrates aresource grid structure in 3GPP LTE/LTE-A. A resource grid is presentper antenna port.

Referring to FIG. 2 , a slot includes a plurality of OFDM (OrthogonalFrequency Division Multiplexing) symbols in the time domain and aplurality of resource blocks (RBs) in the frequency domain. An OFDMsymbol may refer to a symbol period. A signal transmitted in each slotmay be represented by a resource grid composed of N_(RB) ^(DL/UL)*N_(sc)^(RB) subcarriers and N_(symb) ^(DL/UL) OFDM symbols. Here, N_(RB) ^(DL)denotes the number of RBs in a downlink slot and N_(RB) ^(UL) denotesthe number of RBs in an uplink slot. N_(RB) ^(DL) and N_(RB) ^(UL)respectively depend on a DL transmission bandwidth and a UL transmissionbandwidth. N_(symb) ^(DL) denotes the number of OFDM symbols in thedownlink slot and N_(symb) ^(UL) denotes the number of OFDM symbols inthe uplink slot. In addition, N_(sc) ^(RB) denotes the number ofsubcarriers constructing one RB.

An OFDM symbol may be called an SC-FDM (Single Carrier FrequencyDivision Multiplexing) symbol according to multiple access scheme. Thenumber of OFDM symbols included in a slot may depend on a channelbandwidth and the length of a cyclic prefix (CP). For example, a slotincludes 7 OFDM symbols in the case of normal CP and 6 OFDM symbols inthe case of extended CP. While FIG. 2 illustrates a subframe in which aslot includes 7 OFDM symbols for convenience, embodiments of the presentinvention can be equally applied to subframes having different numbersof OFDM symbols. Referring to FIG. 2 , each OFDM symbol includes N_(RB)^(DL/UL)*N_(sc) ^(RB) subcarriers in the frequency domain. Subcarriertypes can be classified into a data subcarrier for data transmission, areference signal subcarrier for reference signal transmission, and nullsubcarriers for a guard band and a direct current (DC) component. Thenull subcarrier for a DC component is a subcarrier remaining unused andis mapped to a carrier frequency (f0) during OFDM signal generation orfrequency up-conversion. The carrier frequency is also called a centerfrequency.

An RB is defined by N_(symb) ^(DL/UL) (e.g., 7) consecutive OFDM symbolsin the time domain and (e.g., 12) consecutive subcarriers in thefrequency domain. For reference, a resource composed by an OFDM symboland a subcarrier is called a resource element (RE) or a tone.Accordingly, an RB is composed of N_(symb) ^(DL/UL)*N_(sc) ^(RB) REs.Each RE in a resource grid can be uniquely defined by an index pair (k,l) in a slot. Here, k is an index in the range of 0 to N_(RB)^(DL/UL)*N_(sc) ^(RB)−1 in the frequency domain and l is an index in therange of 0 to N_(symb) ^(DL/UL)−1.

Two RBs that occupy N_(sc) ^(RB) consecutive subcarriers in a subframeand respectively disposed in two slots of the subframe are called aphysical resource block (PRB) pair. Two RBs constituting a PRB pair havethe same PRB number (or PRB index). A virtual resource block (VRB) is alogical resource allocation unit for resource allocation. The VRB hasthe same size as that of the PRB. The VRB may be divided into alocalized VRB and a distributed VRB depending on a mapping scheme of VRBinto PRB. The localized VRBs are mapped into the PRBs, whereby VRBnumber (VRB index) corresponds to PRB number. That is, nPRB=nVRB isobtained. Numbers are given to the localized VRBs from 0 to N_(VRB)^(DL)−1, and N_(VRB) ^(DL)=N_(RB) ^(DL) is obtained. Accordingly,according to the localized mapping scheme, the VRBs having the same VRBnumber are mapped into the PRBs having the same PRB number at the firstslot and the second slot. On the other hand, the distributed VRBs aremapped into the PRBs through interleaving. Accordingly, the VRBs havingthe same VRB number may be mapped into the PRBs having different PRBnumbers at the first slot and the second slot. Two PRBs, which arerespectively located at two slots of the subframe and have the same VRBnumber, will be referred to as a pair of VRBs.

FIG. 3 illustrates a downlink (DL) subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 3 , a DL subframe is divided into a control region anda data region. A maximum of three (four) OFDM symbols located in a frontportion of a first slot within a subframe correspond to the controlregion to which a control channel is allocated. A resource regionavailable for PDCCH transmission in the DL subframe is referred to as aPDCCH region hereinafter. The remaining OFDM symbols correspond to thedata region to which a physical downlink shared chancel (PDSCH) isallocated. A resource region available for PDSCH transmission in the DLsubframe is referred to as a PDSCH region hereinafter. Examples ofdownlink control channels used in 3GPP LTE include a physical controlformat indicator channel (PCFICH), a physical downlink control channel(PDCCH), a physical hybrid ARQ indicator channel (PHICH), etc. ThePCFICH is transmitted at a first OFDM symbol of a subframe and carriesinformation regarding the number of OFDM symbols used for transmissionof control channels within the subframe. The PHICH is a response ofuplink transmission and carries an HARQ acknowledgment (ACK)/negativeacknowledgment (NACK) signal.

Control information carried on the PDCCH is called downlink controlinformation (DCI). The DCI contains resource allocation information andcontrol information for a UE or a UE group. For example, the DCIincludes a transport format and resource allocation information of adownlink shared channel (DL-SCH), a transport format and resourceallocation information of an uplink shared channel (UL-SCH), paginginformation of a paging channel (PCH), system information on the DL-SCH,information about resource allocation of an upper layer control messagesuch as a random access response transmitted on the PDSCH, a transmitcontrol command set with respect to individual UEs in a UE group, atransmit power control command, information on activation of a voiceover IP (VoIP), downlink assignment index (DAI), etc. The transportformat and resource allocation information of the DL-SCH are also calledDL scheduling information or a DL grant and the transport format andresource allocation information of the UL-SCH are also called ULscheduling information or a UL grant. The size and purpose of DCIcarried on a PDCCH depend on DCI format and the size thereof may bevaried according to coding rate. Various formats, for example, formats 0and 4 for uplink and formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3 and 3Afor downlink, have been defined in 3GPP LTE. Control information such asa hopping flag, information on RB allocation, modulation coding scheme(MCS), redundancy version (RV), new data indicator (NDI), information ontransmit power control (TPC), cyclic shift demodulation reference signal(DMRS), UL index, channel quality information (CQI) request, DLassignment index, HARQ process number, transmitted precoding matrixindicator (TPMI), precoding matrix indicator (PMI), etc. is selected andcombined based on DCI format and transmitted to a UE as DCI.

In general, a DCI format for a UE depends on transmission mode (TM) setfor the UE. In other words, only a DCI format corresponding to aspecific TM can be used for a UE configured in the specific TM.

A PDCCH is transmitted on an aggregation of one or several consecutivecontrol channel elements (CCEs). The CCE is a logical allocation unitused to provide the PDCCH with a coding rate based on a state of a radiochannel. The CCE corresponds to a plurality of resource element groups(REGs). For example, a CCE corresponds to 9 REGs and an REG correspondsto 4 REs. 3GPP LTE defines a CCE set in which a PDCCH can be located foreach UE. A CCE set from which a UE can detect a PDCCH thereof is calleda PDCCH search space, simply, search space. An individual resourcethrough which the PDCCH can be transmitted within the search space iscalled a PDCCH candidate. A set of PDCCH candidates to be monitored bythe UE is defined as the search space. In 3GPP LTE/LTE-A, search spacesfor DCI formats may have different sizes and include a dedicated searchspace and a common search space. The dedicated search space is aUE-specific search space and is configured for each UE. The commonsearch space is configured for a plurality of UEs. Aggregation levelsdefining the search space is as follows.

TABLE 3 Search Space S_(K) ^((L)) Number of PDCCH Type Aggregation LevelL Size[in CCEs] candidates M^((L)) UE-specific 1 6 6 2 12 6 4 8 2 8 16 2Common 4 16 4 8 16 2

A PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs according to CCEaggregation level. An eNB transmits a PDCCH (DCI) on an arbitrary PDCCHcandidate with in a search space and a UE monitors the search space todetect the PDCCH (DCI). Here, monitoring refers to attempting to decodeeach PDCCH in the corresponding search space according to all monitoredDCI formats. The UE can detect the PDCCH thereof by monitoring pluralPDCCHs. Since the UE does not know the position in which the PDCCHthereof is transmitted, the UE attempts to decode all PDCCHs of thecorresponding DCI format for each subframe until a PDCCH having the IDthereof is detected. This process is called blind detection (or blinddecoding (BD)).

The eNB can transmit data for a UE or a UE group through the dataregion. Data transmitted through the data region may be called userdata. For transmission of the user data, a physical downlink sharedchannel (PDSCH) may be allocated to the data region. A paging channel(PCH) and downlink-shared channel (DL-SCH) are transmitted through thePDSCH. The UE can read data transmitted through the PDSCH by decodingcontrol information transmitted through a PDCCH. Informationrepresenting a UE or a UE group to which data on the PDSCH istransmitted, how the UE or UE group receives and decodes the PDSCH data,etc. is included in the PDCCH and transmitted. For example, if aspecific PDCCH is CRC (cyclic redundancy check)-masked having radionetwork temporary identify (RNTI) of “A” and information about datatransmitted using a radio resource (e.g., frequency position) of “B” andtransmission format information (e.g., transport block size, modulationscheme, coding information, etc.) of “C” is transmitted through aspecific DL subframe, the UE monitors PDCCHs using RNTI information anda UE having the RNTI of “A” detects a PDCCH and receives a PDSCHindicated by “B” and “C” using information about the PDCCH.

A reference signal (RS) to be compared with a data signal is necessaryfor the UE to demodulate a signal received from the eNB. A referencesignal refers to a predetermined signal having a specific waveform,which is transmitted from the eNB to the UE or from the UE to the eNBand known to both the eNB and UE. The reference signal is also called apilot. Reference signals are categorized into a cell-specific RS sharedby all UEs in a cell and a modulation RS (DM RS) dedicated for aspecific UE. A DM RS transmitted by the eNB for demodulation of downlinkdata for a specific UE is called a UE-specific RS. Both or one of DM RSand CRS may be transmitted on downlink. When only the DM RS istransmitted without CRS, an RS for channel measurement needs to beadditionally provided because the DM RS transmitted using the sameprecoder as used for data can be used for demodulation only. Forexample, in 3GPP LTE(-A), CSI-RS corresponding to an additional RS formeasurement is transmitted to the UE such that the UE can measurechannel state information. CSI-RS is transmitted in each transmissionperiod corresponding to a plurality of subframes based on the fact thatchannel state variation with time is not large, unlike CRS transmittedper subframe.

FIG. 4 illustrates an exemplary uplink subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 4 , a UL subframe can be divided into a control regionand a data region in the frequency domain. One or more PUCCHs (physicaluplink control channels) can be allocated to the control region to carryuplink control information (UCI). One or more PUSCHs (Physical uplinkshared channels) may be allocated to the data region of the UL subframeto carry user data.

In the UL subframe, subcarriers spaced apart from a DC subcarrier areused as the control region. In other words, subcarriers corresponding toboth ends of a UL transmission bandwidth are assigned to UCItransmission. The DC subcarrier is a component remaining unused forsignal transmission and is mapped to the carrier frequency f0 duringfrequency up-conversion. A PUCCH for a UE is allocated to an RB pairbelonging to resources operating at a carrier frequency and RBsbelonging to the RB pair occupy different subcarriers in two slots.Assignment of the PUCCH in this manner is represented as frequencyhopping of an RB pair allocated to the PUCCH at a slot boundary. Whenfrequency hopping is not applied, the RB pair occupies the samesubcarrier.

The PUCCH can be used to transmit the following control information.

-   -   Scheduling Request (SR): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ ACK/NACK: This is a response signal to a downlink data        packet on a PDSCH and indicates whether the downlink data packet        has been successfully received. A 1-bit ACK/NACK signal is        transmitted as a response to a single downlink codeword and a        2-bit ACK/NACK signal is transmitted as a response to two        downlink codewords. HARQ-ACK responses include positive ACK        (ACK), negative ACK (NACK), discontinuous transmission (DTX) and        NACK/DTX. Here, the term HARQ-ACK is used interchangeably with        the term HARQ ACK/NACK and ACK/NACK.    -   Channel State Indicator (CSI): This is feedback information        about a downlink channel. Feedback information regarding MIMO        includes a rank indicator (RI) and a precoding matrix indicator        (PMI).

The quantity of control information (UCI) that a UE can transmit througha subframe depends on the number of SC-FDMA symbols available forcontrol information transmission. The SC-FDMA symbols available forcontrol information transmission correspond to SC-FDMA symbols otherthan SC-FDMA symbols of the subframe, which are used for referencesignal transmission. In the case of a subframe in which a soundingreference signal (SRS) is configured, the last SC-FDMA symbol of thesubframe is excluded from the SC-FDMA symbols available for controlinformation transmission. A reference signal is used to detect coherenceof the PUCCH. The PUCCH supports various formats according toinformation transmitted thereon. Table 4 shows the mapping relationshipbetween PUCCH formats and UCI in LTE/LTE-A.

TABLE 4 Number of PUCCH Modulation bits per format scheme subframe UsageEtc. 1 N/A N/A (exist SR (Scheduling or absent) Request) 1a BPSK 1ACK/NACK or SR + One ACK/NACK codeword 1b QPSK 2 ACK/NACK or SR + TwoACK/NACK codeword 2 QPSK 20 CQI/PMI/RI Joint coding ACK/NACK (extendedCP) 2a QPSK + 21 CQI/PMI/RI + ACK/ Normal CP BPSK NACK only 2b QPSK + 22CQI/PMI/RI + ACK/ Normal CP QPSK NACK only 3 QPSK 48 ACK/NACK or SR +ACK/NACK or CQI/ PMI/RI + ACK/ NACK

Referring to Table 4, PUCCH formats 1/1a/1b are used to transmitACK/NACK information, PUCCH format 2/2a/2b are used to carry CSI such asCQI/PMI/RI and PUCCH format 3 is used to transmit ACK/NACK information.

Reference Signal (RS)

When a packet is transmitted in a wireless communication system, signaldistortion may occur during transmission since the packet is transmittedthrough a radio channel. To correctly receive a distorted signal at areceiver, the distorted signal needs to be corrected using channelinformation. To detect channel information, a signal known to both atransmitter and the receiver is transmitted and channel information isdetected with a degree of distortion of the signal when the signal isreceived through a channel. This signal is called a pilot signal or areference signal.

When data is transmitted/received using multiple antennas, the receivercan receive a correct signal only when the receiver is aware of achannel state between each transmit antenna and each receive antenna.Accordingly, a reference signal needs to be provided per transmitantenna, more specifically, per antenna port.

Reference signals can be classified into an uplink reference signal anda downlink reference signal. In LTE, the uplink reference signalincludes:

i) a demodulation reference signal (DMRS) for channel estimation forcoherent demodulation of information transmitted through a PUSCH and aPUCCH; and

ii) a sounding reference signal (SRS) used for an eNB to measure uplinkchannel quality at a frequency of a different network.

The downlink reference signal includes:

i) a cell-specific reference signal (CRS) shared by all UEs in a cell;

ii) a UE-specific reference signal for a specific UE only;

iii) a DMRS transmitted for coherent demodulation when a PDSCH istransmitted;

iv) a channel state information reference signal (CSI-RS) for deliveringchannel state information (CSI) when a downlink DMRS is transmitted;

v) a multimedia broadcast single frequency network (MBSFN) referencesignal transmitted for coherent demodulation of a signal transmitted inMBSFN mode; and

vi) a positioning reference signal used to estimate geographic positioninformation of a UE.

Reference signals can be classified into a reference signal for channelinformation acquisition and a reference signal for data demodulation.The former needs to be transmitted in a wide band as it is used for a UEto acquire channel information on downlink transmission and received bya UE even if the UE does not receive downlink data in a specificsubframe. This reference signal is used even in a handover situation.The latter is transmitted along with a corresponding resource by an cNBwhen the cNB transmits a downlink signal and is used for a UE todemodulate data through channel measurement. This reference signal needsto be transmitted in a region in which data is transmitted.

CSI Report

In a 3GPP LTE(-A) system, a user equipment (UE) reports channel stateinformation (CSI) to a base station (BS) and CSI refers to informationindicating quality of a radio channel (or a link) formed between the UEand an antenna port. For example, the CSI includes a rank indicator(RI), a precoding matrix indicator (PMI), a channel quality indicator(CQI), etc. Here, the RI indicates rank information of a channel andmeans the number of streams received by the UE via the sametime-frequency resources. Since the value of the RI is determineddepending on long term fading of the channel, the RI is fed from the UEback to the BS with periodicity longer than that of the PMI or the CQI.The PMI has a channel space property and indicates a precoding indexpreferred by the UE based on a metric such a signal to interference plusnoise ratio (SINR). The CQI indicates the strength of the channel andmeans a reception SINR obtained when the BS uses the PMI.

Based on measurement of the radio channel, the UE may calculate apreferred PMI and RI, which may derive an optimal or best transfer ratewhen used by the BS, in a current channel state and feed the calculatedPMI and RI back to the BS. The CQI refers to a modulation and codingscheme for providing acceptable packet error probability for thefed-back PMI/RI.

Meanwhile, in an LTE-A system which includes more accurate MU-MIMO andexplicit CoMP operations, current CSI feedback is defined in LTE andthus may not sufficiently support operations to be newly introduced. Asrequirements for CSI feedback accuracy become more complex in order toobtain sufficient MU-MIMO or CoMP throughput gain, the PMI is composedof two PMIs such as a long term/wideband PMI (W1) and a shortterm/subband PMI (W2). In other words, a final PMI is expressed by afunction of W1 and W2. For example, the final PMI W may be defined asfollows: W=W1*W2 or W=W2*W1. Accordingly, in LTE-A, a CSI may becomposed of RI, W1, W2 and CQI.

In the 3GPP LTE(-A) system, an uplink channel used for CSI transmissionis shown in Table 5 below.

TABLE 5 Aperiodic CSI Scheduling Scheme Periodic CSI transmissiontransmission Frequency non-selective PUCCH — Frequency selective PUCCHPUSCH

Referring to Table 5, the CSI may be transmitted using a physical uplinkcontrol channel (PUCCH) with periodicity determined by a higher layer ormay be aperiodically transmitted using a physical uplink shared channel(PUSCH) according to the demand of a scheduler. If the CSI istransmitted using the PUSCH, only frequency selective scheduling methodand an aperiodic CSI transmission method are possible. Hereinafter, thescheduling scheme and a CSI transmission scheme according to periodicitywill be described.

1) CQI/PMI/RI Transmission Via PUSCH after Receiving CSI TransmissionRequest Control Signal.

A control signal for requesting transmission of a CSI may be included ina PUSCH scheduling control signal (UL grant) transmitted via a PDCCHsignal. Table 6 below shows the mode of the UE when the CQI, the PMI andthe RI are transmitted via the PUSCH.

TABLE 6 PMI Feedback Type No PMI Single PMI Multiple PMIs PUSCH WidebandMode 1-2 RI 1st CQI (Wideband CQI) wideband Feedback CQI(4 bit) 2nd Typewideband CQI(4 bit) if RI > 1 N*Subband PMI(4 bit) (N is the total # ofsubbands)(if 8Tx Ant, N*subband W2 + wideband W1) UE Mode 2-0 RI (onlyMode 2-2 RI 1st selected for Open-loop SM) wideband (Subband CQI) 1stwideband CQI(4 bit) + Best- CQI(4 bit) + Best- M CQI(2 bit) 2nd MCQI(2bit) wideband (Best-M CQI: CQI(4 bit) + Best- average CQI for MCQI(2 bit) if selected M SB(s) RI > 1 Best-M index among N SBs) (L bit)Wideband Best-M index PMI(4 bit)+ Best-M (L bit) PMI(4 bit) (if 8Tx Ant,wideband W2 + Best-M W2 + wideband W1) Higher Layer- Mode 3-0 RI (onlyMode 3-1 RI 1st Mode 3-2 RI 1st configured for Open-loop SM) widebandwideband (Subband CQI) 1st wideband CQI(4 bit) + CQI(4 bit) + CQI(4bit) + N*subbandCQI N*subbandCQI N*subband (2 bit) 2nd wideband (2 bit)2nd wideband CQI(2 bit) CQI(4 bit) + CQI(4 bit) + N*subbandCQIN*subbandCQI (2 bit) if RI > 1 (2 bit) if Wideband RI > 1N*Subband PMI(4bit) PMI(4 bit) (N is the (if 8Tx Ant, total # of wideband W2 +subbands) (if 8Tx wideband W1) Ant, N*subband W2 + wideband W1)

The transmission mode of Table 6 is selected at a higher layer and theCQI/PMI/RI is transmitted in the same PUSCH subframe. Hereinafter, anuplink transmission method of the UE according to mode will bedescribed.

Mode 1-2 indicates the case in which a precoding matrix is selected onthe assumption that data is transmitted via only a subband with respectto each subband. The UE generates a CQI on the assumption that aprecoding matrix is selected with respect to an entire set S specifiedby a higher layer or a system bandwidth. In Mode 1-2, the UE maytransmit the CQI and the PMI value of each subband. At this time, thesize of each subband may be changed according to system bandwidth.

In mode 2-0, the UE may select M preferred subbands with respect to theset S specified at the higher layer or the system bandwidth. The UE maygenerate one CQI value on the assumption that data is transmitted withrespect to the selected M subbands. The UE preferably reports one CQI(wideband CQI) value with respect to the set S or the system bandwidth.The UE defines the CQI value of each codeword in the form of adifference if a plurality of codewords is present with respect to theselected M subbands.

At this time, the differential CQI value is determined by a differencebetween an index corresponding to the CQI value of the selected Msubbands and a wideband CQI (WB-CQI) index.

In Mode 2-0, the UE may transmit a CQI value generated with respect to aspecified set S or an entire set and one CQI value for the selected Msubbands to the BS. At this time, the size of the subband and the Mvalue may be changed according to system bandwidth.

In Mode 2-2, the UE may simultaneously select the locations of Mpreferred subbands and a single precoding matrix for the M preferredsubbands on the assumption that data is transmitted via the M preferredsubbands. At this time, the CQI value for the M preferred subbands isdefined per codeword. In addition, the UE further generates a widebandCQI value with respect to the specified set S or the system bandwidth.

In Mode 2-2, the UE may transmit information about the locations of theM preferred subbands, one CQI value for the selected M subbands, asingle PMI for the M preferred subbands, a wideband PMI and a widebandCQI value to the BS. At this time, the size of the subband and the Mvalue may be changed according to system bandwidth.

In Mode 3-0, the UE generates a wideband CQI value. The UE generates theCQI value for each subband on the assumption that data is transmittedvia each subband. At this time, even in case of RI>1, the CQI valueindicates only the CQI value for a first codeword.

In Mode 3-1, the UE generates a single precoding matrix with respect tothe specified set S or the system bandwidth. The UE generates a subbandCQI on a per codeword basis on the assumption of the single precodingmatrix generated with respect to each subband. In addition, the UE maygenerate a wideband CQI on the assumption of a single precoding matrix.The CQI value of each subband may be expressed in the form of adifference. The subband CQI value is calculated by a difference betweena subband CQI index and a wideband CQI index. At this time, the size ofthe subband may be changed according to system bandwidth.

In Mode 3-2, the UE generate a precoding matrix for each subband insteadof a single precoding matrix for system bandwidth, to be compared withMode 3-1.

2) Periodic CQI/PMI/RI Transmission Via PUCCH

The UE may periodically transmit the CSI (e.g., CQI/PMI/RI information)to the BS via the PUCCH. If the UE receives a control signal forrequesting transmission of user data, the UE may transmit the CQI viathe PUCCH. Even when the control signal is transmitted via the PUSCH,the CQI/PMI/RI may be transmitted using one of the modes defined inTable 7 below.

TABLE 7 PMI feedback type No PMI Single PMI PUCCH CQI Wideband Mode 1-0Mode 1-1 feedback type (wideband CQI) UE Mode 2-0 Mode 2-1 selection(subband CQI)

The UE may have the transmission modes shown in Table 7. Referring toTable 7, in Mode 2-0 and Mode 2-1, a bandwidth (BP) part is a set ofsubbands continuously located in a frequency domain and may cover asystem bandwidth or a specified set S. In Table 7, the size of eachsubband, the size of the BP and the number of BPs may be changedaccording to system bandwidth. In addition, the UE transmits the CQI ina frequency domain in ascending order per BP so as to cover the systembandwidth or the specified set S.

According to a transmission combination of the CQI/PMI/RI, the UE mayhave the following four transmission types.

i) Type 1: A subband CQI (SB-CQI) of Mode 2-0 and Mode 2-1 istransmitted.

ii) Type 1a: A subband CQI and a second PMI are transmitted.

iii) Type 2, Type 2b, Type 2c: A wideband CQI and a PMI (WB-CQI/PMI) aretransmitted.

iv) Type 2a: A wideband PMI is transmitted.

v) Type 3: An RI is transmitted.

vi) Type 4: A wideband CQI is transmitted.

vii) Type 5: An RI and a wideband PMI are transmitted.

viii) Type 6: An RI and a PTI are transmitted.

If the UE transmits the RI and the wideband CQI/PMI, the CQI/PMI istransmitted in subframes having different offsets and periodicities. Inaddition, if the RI and the wideband CQI/PMI should be transmitted inthe same subframe, the CQI/PMI is not transmitted.

DAI (Downlink Assignment Indicator) in LTE

FDD is a scheme of separately performing downlink (DL) and uplink (DL)transmission and reception with respect to each independent frequencyband. Accordingly, when an eNB transmits a PDSCH in a DL band, a UEtransmits an ACK/NACK response indicating whether complete data has beenreceived to the eNB on a PUCCH of a UL band corresponding to the DL bandafter a specific time. Therefore, the DL band and the UL band operate inone-to-one correspondence.

Specifically, in an example of a legacy 3GPP LTE system, controlinformation about DL data transmission by the eNB is transmitted to theUE on a PDCCH and the UE that has received, on a PDSCH, data scheduledthrough the PDCCH therefor transmits ACK/NACK on a PUCCH which is a UCItransport channel. Generally, the PUCCH for ACK/NACK transmission is notallocated to each UE in advance. Instead, a plurality of UEs dividedlyuses a plurality of PUCCHs at every time point. In order for a UE thathas received DL data at an arbitrary timing to transmit ACK/NACK, the UEuses a PUCCH corresponding to a PDCCH on which the UE has receivedscheduling information about the DL data. More specifically, a region inwhich a PDCCH of each DL subframe is transmitted is comprised of aplurality of control channel elements (CCEs) and a PDCCH transmitted toone UE in an arbitrary subframe is comprised of one or plural CCEs amongCCEs constituting a PDCCH region of the subframe in the arbitrarysubframe. In addition, resources capable of transmitting a plurality ofPUCCHs are present in a region in which a PUCCH of each UL subframe istransmitted. In this case, the UE transmits ACK/NACK on a PUCCH with anindex corresponding to an index of a specific (i.e., first) CCE amongCCEs constituting a PDCCH that the UE has received. FIG. 5 illustrates astructure described above.

In FIG. 5 , each rectangle in a DL component carrier (CC) denotes a CCEand each rectangle in a UL CC denotes a PUCCH. As illustrated in FIG. 5, if one UE acquires PDSCH related information from a PDCCH comprised ofCCEs of indexes 4, 5, and 6 and receives a PDSCH, the UE transmitsACK/NACK on a PUCCH of index 4 corresponding to a CCE of index 4 whichis the first CCE constituting the PDCCH.

Unlike FDD, a TDD scheme uses the same frequency band divided into a DLsubframe and a UL subframe in the time domain. Accordingly, in anasymmetric data traffic situation in DL/UL, more DL subframes may beallocated or more UL subframes may be allocated. In this case, DLsubframes and UL subframes may not be in one-to-one correspondence asopposed to FDD. In particular, if the number of DL subframes is greaterthan the number of UL subframes, a situation occurs in which an ACK/NACKresponse to a plurality of PDSCHs transmitted in a plurality ofsubframes should be processed in one subframe.

In this way, when a plurality of PDSCHs is transmitted to one UE in aplurality of DL subframes, an eNB transmits a plurality of PDCCHs one byone with respect to the PDSCHs. In this case, the UE may transmitACK/NACK on one PUCCH through one UL subframe with respect to thereceived plural PDSCHs. A method of transmitting one ACK/NACK signal fora plurality of PDSCHs broadly includes two schemes as follows.

1) Bundled ACK/NACK transmission (ACK/NACK bundling): The UE transmitsone ACK on one PUCCH upon successful decoding of all received PDSCHs.For the other cases, the UE transmits NACK.

2) PUCCH selective transmission: Upon receiving a plurality of PDSCHs,the UE occupies a plurality of PUCCHs capable of being used for ACK/NACKtransmission using an arbitrary scheme, selects any PUCCH from among theoccupied PUCCHs to transmit ACK/NACK, and transmits a plurality ofACK/NACK signals using a combination of the contents ofmodulation/coding on the selected PUCCH.

The above schemes cause the following problem when the UE transmits anACK/NACK signal to the eNB.

-   -   When the UE misses part of PDCCHs transmitted by the eNB during        several subframes, since the UE is not aware that PDSCHs        corresponding to the missed PDCCHs has been transmitted thereto,        an error may occur in generating ACK/NACK.

To solve such an error, in a TDD system, the eNB includes a DAI in aPDCCH being transmitted to indicate the counted number of PDSCHs to betransmitted on an ACK/NACK resource of one UL subframe, and informs theUE of the number of the PDSCHs. For example, when three DL subframescorrespond to one UL subframe, the eNB sequentially allocates indexes toPDSCHs transmitted in the three DL subframes (i.e., the eNB sequentiallycounts the PDSCHs) and carries the indexes on a PDCCH for scheduling thePDSCHs and then the UE is aware of whether previous PDCCHs have beencorrectly received, through DAI information included in the PDCCH.

In the first example of FIG. 6 , when a UE misses the second PDCCH,since a DAI of the third PDCCH, which is the last PDCCH, is differentfrom the number of PDCCHs received until then, the UE recognizes thatthe second PDCCH has been missed and transmits ACK/NACK according to arecognized result. On the other hand, when the UE misses the last PDCCHas in the second example of FIG. 6 , the UE cannot recognize that thelast PDCCH has been missed because a previous DAI is equal to the numberof PDCCHs received until then. Therefore, the UE may recognize that onlytwo PDCCHs have been scheduled during a DL subframe. In this case, sincethe UE transmits ACK/NACK information through a PUCCH resourcecorresponding to DAI=2 rather than through a PUCCH corresponding toDAI=3, the eNB may recognize that the UE has missed a PDCCH includingDAI=3.

In this case, the aforementioned DAI indicates a DL DAI and is includedin DCI (e.g., a PDCCH or an EPDCCH) indicating PDSCH transmission or DLsemi-persistent scheduling (SPS) release before transmission to the UE.When the eNB triggers UL transmission of the UE at an ACK/NACKtransmission timing, the eNB may include a UL DAI in DCI indicating a ULgrant before transmission to the UE. The UL DAI represents theaccumulated number of PDCCHs/EPDCCHs indicating PDSCH transmission orSPS release for which ACK/NACK transmission is to be performed in agiven duration or, in the case of carrier aggregation (CA), representsthe number of DL subframes in which ACK/NACK is to be transmitted. Uponpiggybacking ACK/NACK on a PUSCH through the UL DAI in the example ofFIG. 6 , the eNB may inform the UE of DAI=3 upon transmission of the ULgrant so that the UE may recognize that the second PDCCH has beenmissed.

The present invention proposes a method for adaptively changing a UCIresource (or a UCI payload size), which is a resource allocated forpiggybacking of UCI of CCs on a UL data channel, for example, a PUSCH,when a massive CA scheme supporting aggregation of a plurality of CCs issupported in a wireless communication system.

In an evolved wireless communication system such as a 3GPP LTE system,characteristics of information in UL are divided into UCI and data and aPUCCH, which is a channel for transmitting the UCI, and a PUSCH, whichis a channel for transmitting the data, are designed according to thecharacteristics of information. However, in a situation in which the UEis not configured to simultaneously transmit the PUCCH and PUSCH, ifPUSCH transmission is present at a timing when the UCI should betransmitted, the UE piggybacks the UCI on the PUSCH being transmitted.FIG. 7 illustrates a scheme of mapping details of UCI, that is.ACK/NACK, a rank indicator (RI), a channel quality indicator(CQI)/precoding matrix indicator (PMI), in a resource region when theUCI is transmitted on a PUSCH in a normal CP. FIG. 7 illustrates thecase in which a PUSCH resource is allocated in one RB in an LTE systemaccording to an embodiment of the present invention, wherein ahorizontal axis represents a single carrier frequency division multipleaccess (SC-FDMA) symbol and a vertical axis represents a subcarrier. Inthis case, a time index of the SC-FDMA symbol increases from a left toright direction and a frequency index of the subcarrier increases from atop to down direction. In addition, different shaded regions areindicated according to types of the UCI and numbers in the same regiondenote mapping orders of coded symbols.

In this case, CQI/PMI is mapped without considering a resource locationof ACK/NACK. Accordingly, if ACK/NACK occupies all SC-FDMA symbols,CQI/PMI in corresponding locations in FIG. 7 is punctured.

In FIG. 7 , as resources to which the UCI is allocated (hereinafter,“UCI resources”) in PUSCH resources occupy a high ratio, resources fortransmitting data are reduced. To efficiently use resources, it isdesirable that the UCI resources be allocated with a minimum amount aslong as performance is guaranteed. Especially, among the types of theUCI, HARQ-ACK desirably reports ACK or NACK for a PDSCH on which actualDL scheduling has been performed, in terms of efficiency of resourceutilization. However, in the above operation, if the UE judges that acorresponding transport block (TB) has not been transmitted due todetection failure of DCI although the eNB has performed DL scheduling ona specific PDSCH, HARQ-ACK configuration reported by the UE (e.g.,HARQ-ACK bundling for PDSCHs detected by the UE) may be different fromHARQ-ACK configuration expected by the eNB (e.g., HARQ-ACK bundling foractually transmitted PDSCHs). As an example, it is assumed that the eNBallocates two DL CCs (e.g., CC₁ and CC₂) to the UE by applying a CAscheme and the UE transmits HARQ-ACK for PDSCHs detected thereby. Then,even when the eNB transmits PDSCHs on CC₁ and CC₂, the UE may succeed indetecting the PDSCH only for CC₂ and report HARQ-ACK for the PDSCHtransmitted on CC₂. Meanwhile, the eNB expects two HARQ-ACK signals fortwo PDSCHs and, even if the eNB recognizes the fact that only oneHARQ-ACK signal has been reported, through a blind detection (BD)scheme, the eNB cannot be aware of on which CC corresponding HARQ-ACKfor a PDSCH has been transmitted.

To solve such a problem, in an LTE system, the eNB configures/setsHARQ-ACK feedback (e.g., a codebook or a payload size) for all potentialPDSCHs on which DL scheduling is capable of being performed for the UEand the UE transmits HARQ-ACK for all PDSCHs. Here, the case in whichthere is no data transmission on a specific PDSCH or the UE fails todetect the PDSCH may be defined as DTX to be reported as HARQ-ACK. Inthis case, DTX may be reported as one state of NACK/DTX together withNACK. As an example, when a CA scheme is applied and HARQ-ACK istransmitted on PUSCH resources in the LTE system, HARQ-ACK is designedto be reported based on PDSCHs that can be transmitted on all CCsconfigured by the eNB for the UE. Meanwhile, in an LTE Rel-10/11/12system, a CA technology for transmitting DL data to the UE by combiningup to 5 CCs has been considered. However, in LTE Rel-13, a massive CAscheme of expanding the number of CCs up to 32 (or 16) has beendiscussed for the purpose of supporting the amount of DL traffic that israpidly increased recently. When the number of CCs which can beconfigured for the UE by the massive CA scheme is greatly increased, ifthe UE reports HARQ-ACK signals for PDSCHs that can be transmitted onall CCs configured for the UE in a UCI piggybacking procedure in PUSCHresources as in the scheme in the legacy LTE system, the ratio of UCIresources in the PUSCH resources is raised and a resource region fordata transmission is reduced. In addition, as most CCs which are to beused in the massive CA scheme are predicted to be configured asresources of an unlicensed band on which PDSCH transmission isopportunistically generated according to a channel sensing result,inefficiency is expected to be much severer.

Accordingly, as methods for adaptively changing a UCI resource as neededwhen UCI piggybacking is performed in PUSCH resources during support ofthe massive CA scheme, the present invention broadly proposes (1) amethod in which the UE transmits a PDSCH on a UCI resourcedistinguishable according to each detected CC group (CG) and (2) amethod in which the cNB directly indicates a CG used for UCIpiggybacking. Hereinafter, while an operation in the LTE system as aspecific embodiment of the present invention will be described, thepresent invention is applicable to arbitrary wireless communicationsystems.

Separate UCI Coding/Resource Mapping for Each CG

UCI Resource for Each CG

According to a specific embodiment of the present invention, a method isproposed in which, when a UE performs UCI piggybacking on PUSCHresources, information about one or more CGs consisting of a pluralityof CCs is directly signaled to the UE from an eNB or previouslyconfigured by a specific rule based on cell indexes and the number ofcells and the UE derives a UCI resource for each CG by applying separatecoding (e.g. a Reed-Muller (RM) code) for each CG after combining UCIcorresponding to all CCs in a corresponding CG with respect to each CG.In this case, the UCI resource may indicate coded bits, a plurality ofcoded symbols, or a plurality of REs, for UCI transmission and adifferent (distinguishable) UCI resource for each CG may beconfigured/allocated. In the present invention, “separate coding foreach CG is applied” means that an input payload of one equal encoder isnot configured by a combination of UCI corresponding to a plurality ofdifferent CGs (i.e., an input payload of each encoder is configured onlyby UCI corresponding to one equal CG).

When the case of HARQ-ACK is considered, a UCI payload size or a UCIresource may be determined, desirably, by taking into considerationwhether DL scheduling of a PDSCH that can be transmitted on each CC hasbeen performed. Although the above scheme can allocate a flexible UCIresource, signaling overhead may increase or complexity in eNBimplementation may increase in order for the UE and the eNB to recognizethe flexible UCI resource. As an example, when the eNB indicates CCs onwhich HARQ-ACK is transmitted, the eNB may add a DAI of a CC domain toDCI for triggering PUSCH resources. That is, the DAI may indicatewhether DL scheduling is performed with respect to a maximum of 32 CCsand, in this case, signaling overhead may significantly increase.Therefore, the present invention proposes a method for introducing theconcept of a CG as a minimum unit capable of adaptively changing a UCIresource in terms of relief of signaling overhead and determining a UCIresource for each CG based on UCI corresponding to all CCs belonging tothe CG without randomly changing the UCI resource by the UE. In thepresent invention, a CG may be composed of one or more cells.

Method for Separately Allocating UCI Resource for Each CG

1. Logical Resource Region

According to a specific embodiment of the present invention, a method isproposed for assigning indexes to REs of a time/frequency resourceregion in PUSCH resources and defining a virtual logical regionaccording to the indexes to separately allocate a UCI resource for eachCG in the logical resource region, when the UE transmits UCIcorresponding to a plurality of CGs on PUSCH resources. In this case, anRE having an i-th index in the logical resource region may be determinedas an RE to which an i-th coded symbol for UCI is allocated among REs ofthe time/frequency resource region in the PUSCH resources.

For example, in the case of HARQ-ACK, indexes 0 to 21 may be assigned toREs transmittable for HARQ-ACK in PUSCH resources in FIG. 7 and alogical resource region according to the indexes may be considered asillustrated in FIG. 8 .

While indexing shown in FIG. 7 is assumed in FIG. 8 , an indexing schemebetween the eNB and the UE may be performed such that indexing isapplied up to the number of REs which can be allocated for UCI or up tothe specific number of REs configured by the eNB. In other words, the UEmay configure a logical resource region for allocating the UCI resourceby assuming the total number of REs which can be allocated for specificUCI in PUSCH resources or configure the logical resource region byconsidering the number of REs calculated under the assumption of a UCIpayload size that the eNB configures through a higher layer signal etc.For example, in the case of HARQ-ACK, when one RB is allocated as thePUSCH resources as illustrated in FIG. 7 , the logical resource regionmay be defined by assigning indexes to 48 REs corresponding to a maximumof four symbols.

1.1 Separate UCI Resource Configuration and UCI Allocation Method forEach CG in Proportion to UCI Payload Size for Each CG

According to a specific embodiment of the present invention, a method isproposed for determining a UCI resource configured by Ntot REs (or Ntotcoded symbols) based on Btot bits which are a UCI payload for all CGs,and defining a separate UCI resource for each CG in a manner of defininga UCI resource for a k-th CG by distributing the Ntot REs in proportionto Bk bits which are a UCI payload of the k-th CG, when the UE transmitsUCI for a plurality of CGs on PUSCH resources and a logical resourceregion configured by ordered REs as in the above scheme is defined. Thatis, if a total of K CGs is present and a separate UCI resource for thek-th CG is N_(k), a separate UCI resource for each CG satisfies arelationship of N₀+N₁+ . . . +N_(K-1)≤Ntot without having overlappingresources (e.g., REs) in the N_(tot) REs.

In the case of HARQ-ACK, for example, in the LTE system according to anembodiment of the present invention, when PUSCH resources aretransmitted in one TB, a UCI resource corresponding to O bits of aHARQ-ACK payload size, i.e., the number of coded symbols, Q′, may bedetermined as follows.

$\begin{matrix}{Q^{\prime} = {\min\left( {\left\lceil \frac{O \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symbol}^{{PUSCH} - {initial}} \cdot \beta_{offset}^{PUSCH}}{\sum\limits_{r - 0}^{C - 1}K_{r}} \right\rceil,{4 \cdot M_{sc}^{PUSCH}}} \right)}} & \left\lbrack {{Math}.1} \right\rbrack\end{matrix}$

where

M_(sc) ^(PUSCH)

is the number of subcarriers of an allocated PUSCH resource in thefrequency domain,

N_(symb) ^(PUSCH-initial)

is the number of SC-FDMA symbols to which the PUSCH resource isallocated, K_(r) is the number of bits transmitted in an r-th codeblock,

β_(offset) ^(PUSCH)

denotes a design parameter, and

∥

denotes a ceiling symbol.

Using [Math. 1], the number of coded symbols, Ntot, when Btot bits,which are a UCI payload size for all CCs (or a CG), are substituted intoa value of O may be calculated. When the payload size of the CG is B_(k)bits, a UCI resource for a k-th CG may be calculated as indicated in[Math. 2] by distributing Ntot REs in proportion to Bk bits which are aUCI payload size of the CG.

$\begin{matrix}{N_{k} = {\min\left\{ {\left\lceil {N_{tot}\frac{B_{k}}{B_{tot}}} \right\rceil,{N_{tot} - S_{k}}} \right\}}} & \left\lbrack {{Math}.2} \right\rbrack\end{matrix}$${{{where}S_{k}} = {\sum\limits_{l - 0}^{k - 1}N_{l}}},{S_{0} = 0}$

In this case, UCI for each CG is generated in the form of a mother codeto which a coding scheme such as RM coding is applied. If the number ofbits of the mother code is less than the number of bits capable of beingtransmitted in the separate UCI resource, circular repetition isperformed and, if the number of bits of the mother code is greater thanthe number of bits capable of being transmitted in the separate UCIresource, a rear part of the mother code is truncated and rate-matchedso as to be transmitted on the separate UCI resource.

1.2 Ordered Allocation in Logical Resource Region

According to a specific embodiment of the present invention, a method isproposed in which the UE transmits UCI for a plurality of CGs on a PUSCHresource and a logical resource region consisting of ordered REs as inthe above scheme is defined, priority information (order information)about the multiple CGs is directly signaled to the UE from the eNB orpreviously configured by a specific rule based on CG indexes and the UEsequentially allocates a UCI resource for each CG to the logicalresource region according to priority (or order) of the CGs.

That is, a UCI resource for a CG having an (n+1)-th priority (or order)is allocated starting from the next RE of an RE to which a UCI resourcefor a CG having an n-th priority (or order) has been allocated. In thiscase, in order to allocate a UCI resource for a specific m-th CG, L REsare needed and, if the remaining number of REs through orderedallocation is less than L or if there are no remaining REs, the UE maynot allocate the UCI resource for the m-th CG.

Hereinafter, in order to clearly explain an operation in the presentinvention, a method for deriving a UCI resource (e.g., a plurality ofREs or a plurality of coded symbols or coded bits, for UCI transmission)of a specific CG will be defined using the following two methods.

-   -   First Method: After all UCI resources in PUSCH resources based        on a UCI payload size of Btot bits for all CGs are derived as        Ntot REs or the number of coded symbols, Ntot REs are        distributed in proportion to a UCI payload size of Bk bits of a        k-th CG, thereby determining a UCI resource for each CG so as        not to overlap between the CGs.

(Example) The Case in which One TB is Transmitted in the LTE System

First, the number of coded symbols, N_(tot), in PUSCH resources may bederived as indicated in [Math. 3], based on B_(tot) bits of an entireUCI payload size.

$\begin{matrix}{N_{tot} = {\min\left( {\left\lceil \frac{B_{tot} \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symbol}^{{PUSCH} - {initial}} \cdot \beta_{offset}^{PUSCH}}{\sum\limits_{r = 0}^{C - 1}K_{r}} \right\rceil,{4 \cdot M_{sc}^{PUSCH}}} \right)}} & \left\lbrack {{Math}.3} \right\rbrack\end{matrix}$

where

M_(sc) ^(PUSCH)

is the number of subcarriers of an allocated PUSCH resource in thefrequency domain,

N_(symb) ^(PUSCH-initial)

is the number of SC-FDMA symbols to which the PUSCH resource isallocated, K_(r) is the number of bits transmitted in an r-th codeblock,

β_(offset) ^(PUSCH)

denotes a design parameter, and

┌ ┐

denotes a ceiling symbol. Next, the number of coded symbols (or codedbits), N_(k), for a k-th CG may be calculated as indicated in [Math. 2]when a payload size of the corresponding CG is Bk bits. In this case,UCI resources for respective CGs do not have overlapped resources (e.g.,coded symbols or REs) in the N_(tot) coded symbols.

-   -   Second Method: A UCI resource (e.g., coded symbols or coded bits        for UCI transmission) is derived based on a UCI payload size of        each CG.

(Example) The Case in which One TB is Transmitted in the LTE System

In the second method, the number of coded symbols, N_(k), in PUSCHresources may be derived based on a UCI payload size B_(k) for aspecific k-th CG as indicated in [Math. 4].

$\begin{matrix}{N_{k} = {\min\left( {\left\lceil \frac{B_{k} \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symbol}^{{PUSCH} - {initial}} \cdot \beta_{offset}^{PUSCH}}{\sum\limits_{r = 0}^{C - 1}K_{r}} \right\rceil,{4 \cdot M_{sc}^{PUSCH}}} \right)}} & \left\lbrack {{Math}.4} \right\rbrack\end{matrix}$

For convenience of description of the present invention, a UCI resourcefor each CG calculated according to First Method described above (or aUCI resource for each CG distinguished not to have overlapped resourcesbetween different CGs with respect to all UCI resources) calculatedaccording to the above first method is referred to as “UCI resource type1 for each CG” and a UCI resource for each CG calculated according toSecond Method described above is referred to as “UCI resource type 2 foreach CG”.

Hereinafter, a method for mapping the UCI resource for each CG to alogical resource consisting of ordered REs will be described.

(1) Method for Sequentially Allocating UCI Resource Type 1 for Each CGin a Logical Resource Region

Specifically, the present invention proposes a method for transmittingUCI for each CG as UCI resource type 1 for each CG, which does notinclude overlapped REs defined as in section 1.1. In this case, UCI foreach CG may be generated in the form of a mother code to which a codingscheme such as RM coding is applied. If the number of bits of the mothercode is less than the number of bits capable of being transmitted in UCIresource type 1, circular repetition is performed and, if the number ofbits of the mother code is greater than the number of bits capable ofbeing transmitted in UCI resource type 1, a rear part of the mother codemay be truncated and rate-matched so as to be transmitted in UCIresource type 1. In this case, all UCI resources (or a logical resourceregion) may have a structure in which UCI resource type 1 of each CG issequentially present according to an index or priority of the CG.

For example, it is assumed that the logical resource region asillustrated in FIGS. 7 and 8 is defined, UCI resource type 1 for CG₁includes 11 REs, and UCI resource type 1 for CG₂ includes 11 REs. Inthis case, UCI resource type 1 for CG₁ and UCI resource type 1 for CG₂may be sequentially allocated in the logical resource region asillustrated in FIG. 9 .

(2) Method for Allocating UCI Resource Type 2 for a Specific CG afterPerforming a Procedure of (1)

Meanwhile, due to a restriction on maximum UCI resources capable ofbeing allocated for UCI transmission in PUSCH resources, UCI resourcetype 1 for each CG may have a value less than UCI resource type 2 foreach CG calculated to guarantee coding rate based on a UCI payload foreach CG. In this case, if specific CG₁ mainly consists of CCs in alicensed band and CG₂ mainly consists of CCs in an unlicensed band, UCItransmission for CG₁ which is relatively sensitive to a HARQ processtiming may be prioritized. As described in the above example, if UCIresource type 1 for a specific CG having a high priority of UCItransmission is less than UCI resource type 2, part of UCI resources forCGs having a lower priority than the specific CG may be designed to beallocated to UCI resource type 2 for a CG having a high priority.Alternatively, as in (1), all UCI resources may be divided in units ofUCI resource type 1 for each CG and a CG having a high priority maygenerate a coded symbol based on UCI resource type 2 so that UCIresource type 1 of a CG having a lower priority may be punctured.

For example, it is assumed that UCI resource type 1 for each CG issequentially allocated to be distinguished with respect to all UCIresources (or a logical resource region) in PUSCH resources through theprocedure of (1). In this case, in a process of sequentially allocatingUCI, if a priority of a CG (e.g., CG₁) to which n-th UCI is allocated ishigher than a priority of a CG (e.g., CG₂) to which (n+1)-th UCI isallocated, UCI for CG₁ may be first allocated up to the unit of UCIresource type 1 for CG₁ by performing coding in units of UCI resourcetype 2 and the remaining part of UCI resource type 2 for CG₁ may besequentially allocated stating from the front part in UCI resource type1 for CG₂. In this case, UCI for CG₂ may be sequentially allocated afterUCI resource allocation for CG₁ in UCI resource type 1 is ended. FIG. 10illustrates the above example.

Alternatively, UCI for CG₂ in the above example is allocated by applyingcoding based on UCI resource type 1 for CG₂ as illustrated in FIG. 10and UCI for CG₁ may be allocated to UCI resource type 1 for CG₁ byapplying coding in units of UCI resource type 2 and the remaining UCIresources may be allocated in a manner of puncturing the front part ofUCI resource type 1 for CG₂. FIG. 11 illustrates the above example.

(3) Method for Sequentially Allocating UCI Resource Type 2 for Each CGin a Logical Resource Region

When priority between CGs is important, a method may be considered forsequentially allocating UCI resources in units of UCI resource type 2for each CG in order of prioritized CGs without considering UCI resourcetype 1. As an example, in the case of HARQ-ACK, it is assumed that alogical resource region is defined as illustrated in FIGS. 7 and 8 , UCIresource type 2 for CG₁ includes 15 REs, and UCI resource type 2 for CG₂includes 12 REs. Then, UCI resource type 2 for CG₁ and UCI resource type2 for CG₂ may be sequentially allocated as illustrated in (a) or (b) ofFIG. 12 .

In this case, (a) of FIG. 12 illustrates transmission even when UCIresources for CG₂ are truncated and (b) of FIG. 12 illustrates omissionof UCI transmission for CG₂.

1.3 Starting Index and Ending Index Based Allocation in a LogicalResource Region

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs onPUSCH resources and a logical resource region consisting of sequentialREs as described in the above scheme is defined, the eNB configures, forthe UE, a starting index and an ending index (or a starting index andthe number of allocated REs) in the logical resource region for UCIresource allocation for each CG and the UE allocates a UCI resource foreach CG up to the ending index from the starting index. In this case, ifthe number of REs necessary for UCI resource allocation in terms ofcoding gain for a specific CG is greater than the number of REsallocated by the eNB, UCI resource transmission for the CG may beomitted.

For example, in the case of HARQ-ACK, it is assumed that the logicalresource region is defined as illustrated in FIGS. 7 and 8 , a UCIresource for CG₁ includes 15 REs, and a UCI resource for CG₂ includes 12REs. Then, if the eNB configures the starting index and the ending indexof UCI resource allocation for CG₁ and CG₂ as (0, 10) and (11, 21),respectively, UCI resources for the respective CGs may be allocated asin indicated in FIG. 13 .

1.4 Starting Index and Puncturing Operation Based Allocation in LogicalResource Region

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs onPUSCH resources and a logical resource region consisting of sequentialREs as in the above scheme is defined, the eNB informs the UE ofpriority information (or order information) for CGs and a starting indexin the logical resource region for UCI resource allocation for each CGand the UE allocates UCI resources starting from a CG having a lowpriority (or a late order) and allocates a UCI resource for a CG havinga high priority (or an early order) in a manner of puncturing the UCIresources for CG having a low priority.

For example, in the case of HARQ-ACK, it is assumed that the logicalresource region is defined as illustrated in FIG. 8 , a UCI resource forCG₁ includes 15 REs, a UCI resource for CG₂ includes 12 REs, and CG₁ hasa higher priority than CG₂. Then, a UCI resource for each CG may betransmitted as indicated in FIG. 14 according to the above scheme.

Starting index/ending index based allocation and startingindex/puncturing operation based allocation, described above, may beapplied through a combination thereof. That is, UCI resource for CGshave a stating index and may be allocated while puncturing alreadyallocated resources or may be allocated up to the ending index accordingto whether the eNB configures resources.

As described above, a UCI resource may be expressed by REs of physicallocations in a time/frequency resource region by a mapping relationshipbetween a logical resource region and the time/frequency resourceregion. As an example, UCI resources for two CGs are distinguished onlogical resources as illustrated in FIG. 13 , the UCI resources may berepresented as actual physical resources as indicated in FIG. 15 by amapping relationship between FIGS. 7 and 8 .

Similarly, the UCI resources in FIG. 14 may be represented by actualphysical resources as illustrated in FIG. 16 .

2. Time/Frequency Resource Region

2.1. Method for Allocating a UCI Resource for Each CG to a DifferentSC-FDMA Symbol

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs onPUSCH resources, the eNB configures, for the UE, a resource region inwhich a UCI resource for each CG can be allocated by a plurality ofSC-FDMA symbols and configures SC-FDMA symbol sets to which UCIresources for different CGs are allocated not to be equal.Alternatively, more generally, the eNB may allocate UCI resources forCGs to distinguishable time resources.

For example, in the case of HARQ-ACK, a maximum region in which codedsymbols of HARQ-ACK can be allocated in PUSCH resources may be 4 SC-FDMAsymbols (i.e., SC-OFDM symbols of indexes 2, 4, 9, and 11) adjacent to aPUSCH demodulation reference signal (DM-RS) as illustrated in FIG. 7 .Assuming that the UE transmits UCI for two CGs (e.g. CG₁ and CG₂) onPUSCH resources, a maximum resource region in which a UCI resource forCG₁ may be configured by SC-FDMA symbols of indexes 2 and 4 and amaximum resource region in which a UCI resource for CG₂ may beconfigured by SC-FDMA symbols of indexes 9 and 11

FIG. 17 illustrates the case in which a UCI resource for CG₁ includes 15REs and a UCI resource for CG₂ includes 12 REs.

2.2 Method for Allocating a UCI Resource for CG to a Different RB

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs onPUSCH resources, the cNB configures, for the UE, a resource region inwhich a UCI resource for each CG can be allocated by a plurality of RBsand configures RB sets to which UCI resources for different CG areallocated not to be equal. Alternatively, more generally, the eNB mayallocate UCI resources for CGs to distinguishable frequency resources.

For example, in the case of HARQ-ACK, assuming that the UE transmits UCIfor two CGs (e.g. CG₁ and CG₂) on PUSCH resources consisting of 2 RBs,UCI resources for CGs may be allocated to be distinguished in differentRBs.

Method for Selectively Transmitting UCI for Each CG

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs onPUSCH resources and (after separate coding for each CG is applied), asin the UCI resource allocation scheme for each CG, UCI resources for CGsare distinguished in a resource region, the UE selectively transmits UCIfor a specific CG and the eNB detects whether UCI for a specific CG hasbeen transmitted by performing BD in each resource region to which a UCIresource for each CG is applied. In this case, the cNB may first detectUCI for a CG having a high priority (or an early order). In this case,the UE does not transmit UCI for a CG for which a PDSCH/PDCCH (requiringACK/NACK feedback) is not received and fills a corresponding UCIresource with data. In other words, (with respect to each CG) when thereis no scheduling for all cells belonging to the CG, data may not bepunctured on a UCI resource corresponding to the CG. Conversely, whenthere is scheduling for at least one cell belonging to the CG, data maybe punctured on a UCI resource corresponding to the CG and UCI (e.g.,ACK/NACK) corresponding to the CG may be mapped.

For example, in FIG. 8 , when PDSCH scheduling is not present at areference timing of HARQ-ACK transmission for CG₁ and there is noHARQ-ACK information to be transmitted for CG₁, UCI for CG₁ may not betransmitted and data transmission may be performed on a correspondingUCI resource.

[Exemplary CG Configuration]

When a cell defined in a licensed band is referred to as L-cell and acell defined in an unlicensed band is referred to as U-cell, one of thefollowing CG configurations may be considered as an exemplary CGconfiguration capable of using the above proposed scheme.

(1) A CG (CG₁) consisting only of the L-cell and a CG (CG₂) consistingonly of the U-cell

(2) A CG (CG₁) consisting only of the L-cell and a CG (CG₂) includingthe U-cell and the L-cell

(3) A CG (CG₁) including the L-cell and the U-cell and a CG (CG₂)consisting only of the U-cell

(4) A CG (CG₁) consisting only of the L-cell, a CG (CG₂) including theL-cell and the U-cell, and a CG (CG₃) consisting only of the U-cell

In the U-cell, opportunistic PDSCH transmission is performed based on alisten-before-talk (LBT) operation. Therefore, in the examples of (1),(2), and (3), CG₂ includes many U-cells so that a probability ofperforming PDSCH transmission is low relative to CG₁.

For example, in the above exemplary CG configuration, if PDSCHtransmission only on CG₁ is present and PDSCH transmission on CG₁ is notpresent, HARQ-ACK for CG₁ may be transmitted on a UCI resourcecorresponding to CG₁ by applying separate coding and HARQ-ACK for CG₁may be omitted.

As an example, in the case of HARQ-ACK, the UE in an FDD system of LTEmay transmit HARQ-ACK for PDSCH transmission at a specific timingthrough UCI piggybacking on a PUSCH. If there is no PDSCH transmitted atthe specific timing, the UE may not allocate coded symbols for HARQ-ACKon a PUSCH resource (e.g., DTX). In this case, the cNB may determinewhether the UE has performed HARQ-ACK reporting by performing BD underthe assumption that coded symbols for HARQ-ACK have been allocated.Accordingly, in a legacy LTE system, it can be assumed that the eNB hasa BD capability to determine whether HARQ-ACK transmission has beenperformed.

However, the BD capabilities of the eNB are expected to determine onlywhether UCI has been transmitted, when a prescheduled UCI payload size(or a UCI resource) in a prescheduled resource region is assumed. Forexample, assuming that 5 CCs in total are configured for the UE and aPDSCH is transmitted on two of the 5 CCs so that the UE reports HARQ-ACKonly for the two CCs through a PUSCH, the eNB has a probability ofdetermining that HARQ-ACK for the two CCs has been reported byperforming BD but cannot be aware of which of the 5 CCs correspond tothe two CCs.

Therefore, the present invention may define a UCI resource for each CGwhich can be recognized between the eNB and the UE and separatelyallocate the UCI resource for each CG in a resource region so as tosupport BD of the eNB for determining whether UCI transmission for eachCG has been performed. When a massive CA scheme is applied, the aboveoperation enables the UE to efficiently use resources by causing the UEto omit HARQ-ACK transmission in the case of detection failure of the UEor with respect to a specific CG in which HARQ-ACK of PDSCHs for all CCsin the CG is NACK/DTX.

Hereinafter, a method will be described for expanding the concept of aDAI in a TDD system, when the UE transmits UCI for a plurality of CGsthrough a PUSCH and UCI for respective CGs is different.

Explicit Signaling Based UCI Resource Adaptation of eNB

A description given below considers the following exemplary CGconfiguration.

[Exemplary CG Configuration]

When a cell defined in a licensed band is referred to as L-cell and acell defined in an unlicensed band is referred to as U-cell, thefollowing CG configurations may be considered as an exemplary CGconfiguration capable of using the above proposed scheme.

(1) A CG (CG₁) consisting only of the L-cell and a CG (CG₂) consistingonly of the U-cell

(2) A CG (CG₁) consisting only of the L-cell and a CG (CG₂) includingthe U-cell and the L-cell

(3) A CG (CG₁) including the L-cell and the U-cell and a CG (CG₂)consisting only of the U-cell

(4) A CG (CG₁) consisting only of the L-cell, a CG (CG₂) including theL-cell and the U-cell, and a CG (CG₃) consisting only of the U-cell

In the U-cell, opportunistic PDSCH transmission is performed based on anLBT operation. Therefore, in the examples of (1), (2), and (3), CG₂includes many U-cells so that a probability of performing PDSCHtransmission is low relative to CG₁.

If a PDSCH transmission opportunity differs according to each CG, howmany times corresponding UCI transmissions are performed may also bedifferent. Accordingly, the present invention proposes a method in whichthe eNB explicitly indicates a UCI resource for each (or a UCI payloadsize) through explicit signaling in consideration of the case in whichthe number of UCI transmissions for each CG is different.

UL Signaling

1. UL DAI Transmission for Each CG

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs on aPUSCH resource by applying the UCI piggybacking scheme including theaforementioned proposal, for example, by applying separate coding foreach CG or applying coding for all UCI without distinguishing betweenthe CGs, the eNB informs the UE of a UL DAI for each CG as the number ofDL subframes that should be considered when the UE calculates a UCIresource (or UCI payload size) for each CG. The UL DAI for value CG maybe included in control signaling (e.g., DCI) indicating transmission ofthe PUSCH resource.

Due to an asymmetric structure of DL/UL subframes in a TDD system ofLTE, the case in which HARQ-ACK for a plurality of DL subframes shouldbe transmitted in one UL subframe may occur. In the case, the LTE systemhas introduced a DL DAI and a UL DAI that indicate the accumulatednumber of DL subframes in which PDSCHs are transmitted within apredetermined DL subframe duration in order to consider the number of DLsubframes in which PDSCH transmission has been actually performed in aHARQ-ACK payload size. For example, when N PDSCHs in total aretransmitted, the UE may recognize an n-th (where n=0, 1, 2, . . . , N−1)transmitted PDSCH through the DL DAI. Therefore, even when the UE failsto detect some PDSCHs, since the UE is aware of dropped PDSCHs throughthe DL DAI and of the total number of PDSCHs through the UL DAI, the UEmay report HARQ-ACK for the N PDSCHs in total by processing HARQ-ACK forthe detection-failed PDSCHs as DTX.

When a CA scheme is considered in the TDD system, the UE may transmitHARQ-ACK for a plurality of CCs on a PUSCH resource and the number of DLsubframes indicated by the UL DAI is identically applied to all of theCCs. For example, if the number of DL subframes in which PDSCHs havebeen actually transmitted is 3 for CC1 and 1 for CC2, the UL DAI may betransmitted to indicate 3 which is the maximum number of DL subframesfor the two CCs. Then, the UE configures HARQ-ACK under the assumptionthat 3 DL subframes have been transmitted for both CC1 and CC2 andreports HARQ-ACK for CC2 as DTX except for one DL subframe. In this way,when a uniform UL DAI value is applied to a plurality of CCs asdescribed above, inefficient UCI resource allocation may be performedbecause HARQ-ACK for CCs having few DL subframes in which actual PDSCHtransmission is performed is mainly reported as DTX.

In a legacy LTE Rel-12 system, since only the case in which the numberof CCs supported by the CA scheme is up to 5 has been considered,inefficiency when a UL DAI for all CCs is uniformly applied as describedabove has been overlooked. However, when a massive CA scheme isintroduced in an LTE Rel-13 system, such a problem may be pointed outbecause a maximum of 32 CCs is considered. That is, a deviation of thenumber of DL subframes in which PDSCH transmission is performed on 32CCs may become much severer than a deviation of the number of DLsubframes in which PDSCH transmission is performed on 5 CCs. To solvethe above problem, the present invention proposes a method forindependently configuring a UL DAI in units of CGs by informing the UEof the UL DAI in units of CGs. In the above example, the eNB may directthe UE to omit HARQ-ACK transmission for CG₂ by setting a DAI for CC1 toa value corresponding to 3 DL subframes and a DAI for CC2 to a valuecorresponding to one DL subframe.

For example, in the above exemplary CG configuration, if PDSCHtransmission for CG₁ is performed in 4 DL subframes and PDSCHtransmission for CG₂ is performed in one DL subframe, the eNB mayindicate 4 DL subframes as a UL DAI for CG₁ and one DL subframe as a ULDAI for CG₂ to the UE through DCI according to a UL DAI transmissionscheme for each CG.

FIG. 20 illustrates a structure supporting a UL DAI for each CG withrespect to a maximum of two CGs (e.g., CG₁ and CG₂) in DCI format 0.

In FIG. 20 , a CIF is a carrier indicator field, 0/1A is a field fordistinguishing between DCI format 0 and DCI format 1A, FH+Contiguous RAis a field indicating contiguous resource allocation together withfrequency hopping or non-hopping, multi-clustered RA is a fieldindicating multi-cluster based resource allocation, MCS/RV is a fieldindicating a combination of a modulation and coding scheme (MCS) and aredundancy version (RV), NDI (new data indicator) is a field indicatingwhether new data is transmitted, DM-RS CS is a field indicating cyclicshift of a DM-RS, CQI req. is a field indicating the contents ofaperiodic CSI reporting, SRS is a field indicating whether an SRS istransmitted, and RAT is a field indicating a resource allocation type(i.e. consecutive resource allocation or multi-clustered resourceallocation). As indicated in the example, when the UL DAI for each CG istransmitted, multiple UL DAIs for a plurality of CGs may be transmittedas one method.

As an additional operation of the UL DAI transmission scheme for eachCG, the cNB may transmit a single bit field to the UE through dynamicsignaling such as DCI and indicate, through the bit field, UL DAI values(or the numbers of DL subframes) applied to UCI piggybacking for aplurality of CGs. That is, one state of the bit field may indicate acombination of UL DAI values (or the numbers of DL subframes) for aplurality of CGs. For example, in the case of a 2-bit field, each statemay be defined as indicated in Table 8.

TABLE 8 State of 2-bit field Combination of UL DAIs for multiple CGs 00UL DAI = 1 for CG₁, UL DAI = 1 for CG₂ 01 UL DAI = 2 for CG₁, UL DAI = 2for CG₂ 10 UL DAI = 3 for CG₁, UL DAI = 2 for CG₂ 11 UL DAI = 4 for allCGs

2. UCI Piggyback on/Off Indicator Transmission for Each CG

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs on aPUSCH resource by applying the UCI piggybacking scheme including theaforementioned proposal, for example, by applying separate coding foreach CG or applying coding for all UCI without distinguishing betweenthe CGs, the eNB transmits an on/off indicator indicating whether UCIpiggybacking for each CG for specific UCI is performed, as informationabout a CG that should be considered in a UCI resource (or UCI payloadsize) calculation process of the UE. The UCI piggyback on/off indicatorfor each CG may be included in control signaling (e.g., DCI) indicatingPUSCH resource transmission.

For example, in the exemplary CG configuration of the explicit signalingbased UCI resource adaptation scheme of the eNB, if PDSCH transmissionon CG₁ is present and PDSCH transmission on CG₂ is not present, the eNBmay instruct the UE to piggyback UCI for CG₁ on a PUSCH resource (i.e.,“on”) and instruct the UE not to piggyback UCI for CG₂ on a PUSCHresource (i.e., “off”), through a UCI piggyback on/off indicatoraccording to the UCI piggyback on/off indicator transmission scheme foreach CG.

When UCI piggyback is performed on a PUSCH resource in the case in whicha massive CA scheme is applied in the FDD system, if UCI for all CCsconfigured by the eNB for the UE as in a legacy LTE system (e.g.,Rel-10/11/12), UCI signaling overhead may significantly increase.Accordingly, in the FDD system, an operation may be useful in which theeNB instructs the UE to omit UCI transmission for a specific CC (e.g.,CG₂ in the exemplary configuration in the explicit signaling based UCIresource adaptation scheme of the eNB) through the UCI piggyback on/offindicator for each CG as in the above proposed scheme in order to reduceUCI signaling overhead.

When a massive CA scheme is applied in a TDD system, if the eNB informsthe UE of a UL DAI for each CG as in the UL DAI transmission scheme foreach CG, the UE may more efficiently configure a UCI payload size (or aUCI resource) corresponding to the maximum number of DL subframes inwhich PDSCH transmission for each CG is performed. However, the abovemethod requires UL DAIs for a plurality of CGs in DCI indicating PUSCHresource transmission and thus DL control signaling overhead mayincrease. Therefore, the present invention proposes a method fortransmitting an on/off indicator indicating whether UCI piggyback forspecific UCI for each CG is performed as a simpler method. For example,in the case of HARQ-ACK, if a UCI piggyback on/off indicator for CG₁ inDCI representing a PUSCH resource indicates an “off” state, the UE mayomit UCI transmission for corresponding CG₁ and fill the correspondingUCI resource with data.

In this case, an existing UL DAI field for the TDD system may betransmitted together with the UCI piggyback on/off indicator for each CGand the UL DAI may be effectively applied only to CCs for which the UCIpiggyback on/off indicator indicates an “on” state. FIG. 21 illustratesa structure supporting the UCI piggyback on/off indicator for each CGwith respect to a maximum of two CGs (e.g., CG₁ and CG₂) in DCI format0. As another method, in the TDD system, only the UCI piggyback on/offindicator may be configured to be transmitted in a state in which UL DAIfield configuration and signaling are omitted. Alternatively, for aspecific CG, a UL DAI may be transmitted and, for another CC, a UCIpiggyback on/off indicator may be transmitted.

3. Method for Independently Configuring, for Each CC, the Number of DLSubframes Corresponding to a UL DAI

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs on aPUSCH resource by applying the UCI piggybacking scheme including theseparate coding/resource mapping scheme, for example, by applyingseparate coding for each CG or applying coding for all of the UCIwithout distinguishing between CGs, the eNB informs, through a higherlayer signal, the UE of information about a CG to which a specific ULDAI is applied and the number of DL subframes corresponding to the ULDAI through independent configuration for each CC and, after receivingthe UL DAI from the eNB, the UE independently interprets the number ofDL subframes which should be considered for UCI transmission indicatedby a UL DAI for each CG with respect to a CG to which the UL DAI isapplied. That is, the cNB may configure the UE to differently interpreta UL DAI according to each CG so that the UE maintains interpretation ofa UL DAI with respect to a specific CG and differently interprets all orsome of UL DAIs for other specific CGs.

The method for transmitting a UL DAI value for each CG to the UEaccording to the UL DAI transmission scheme for each CG has an advantageof efficiently allocating a UCI resource within PUSCH resources byinforming the UE of the number of DL subframes which should beconsidered during UCI transmission for each CG. However, the UL DAItransmission method for each CG requires a multi-DAI structure asillustrated in FIG. 20 and control signaling overhead increasesaccording to such a structure.

Meanwhile, in the massive CA scheme to which the present invention isapplied, some CCs are configured in a licensed band in which PDSCHtransmission is stable and the other CCs may be configured in anunlicensed band in which PDSCH transmission is opportunisticallygenerated. In this case, when the TDD system is considered, the numberof DL subframes in which PDSCH transmission is present on CCs configuredin the unlicensed band may be relatively fewer than that on CCsconfigured in the licensed band.

In this aspect, according to the exemplary CG configuration in theexplicit signaling based UCI resource adaptation scheme of the eNB, therange of the number of DL subframes in which a PDSCH can be transmittedon CG₂ may be less than that on CG₁ when CG₁ mainly consists of CCs ofthe licensed band and CG₂ mainly consists of CCs of the unlicensed band.Accordingly, it may be desirable that a DL subframe indicated by a ULDAI be differently interpreted for each CG. As an example, in asituation in which a CA scheme of an Rel-12 LTE system is applied, ifTDD UL/DL configuration is {1, 2, 3, 4, 6} and HARQ-ACK is piggybackedon a PUSCH, the UE may map a UL DAI (e.g., W_(DAI) ^(UL)) to the numberof DL subframes (e.g., B_(c) ^(DL)) as described in Reference 1.

[Reference 1]

-   -   For TDD UL/DL configurations {1, 2, 3, 4, 6} and a PUSCH        transmission adjusted based on a detected PDCCH/EPDCCH with DCI        format 0/4, the UE shall assume B_(c) ^(DL)=W_(DAI) ^(UL). The        UE shall not transmit HARQ-ACK on PUSCH if the UE does not        receive PDSCH or PDCCH/EPDCCH indicating downlink SPS release in        subframe(s) n-k where k∈K and W_(DAI) ^(UL)=4.

As one example of applying the operation of the present invention, (ifthe number of DL subframes in which ACK/NACK feedback timings correspondcommonly to one UL subframe is defined as M) the eNB configures, for theUE, the maximum number of DL subframes in which a PDSCH is scheduled foreach CG through a higher layer signal such as radio resource control(RRC) as N_(DL,max,c,) (<M) and the UE may calculate the number of DLsubframes in which a PDSCH is scheduled as indicated in [Math. 5] byapplying the maximum number of DL subframes indicated by N_(DL,max,c).B _(c) ^(DL)=min{W _(DAI) ^(UL) ,N _(DL,max,c)}  [Math. 5]

For a licensed band CC CG₁, a mapping relationship between a UL DAI anda DL subframe, proposed in Reference 1 may be applied and, for anunlicensed band CC CG₂, a mapping relationship between a UL DAI and a DLsubframe may be applied, in which the number of DL subframes in which aPDSCH is scheduled on CG₂ is limited to a maximum of N_(DL,max,c) asindicated in [Math. 5].

In addition, for TDD UL/DL configuration 5 and the case in whichHARQ-ACK is piggybacked on a PUSCH, the UE may map a UL DAI (e.g.,

W_(DAI) ^(UL)

) to the number of DL subframes (e.g.,

B_(c) ^(DL)

) as described in Reference 2.

[Reference 2]

-   -   For TDD UL/DL configurations 5 and a PUSCH transmission adjusted        based on a detected PDCCH/EPDCCH with DCI format 0/4, the UE        shall assume        B _(c) ^(DL) =W _(DAI) ^(UL)+4|(U−W _(DAI) ^(UL))/4|,

where U denotes the maximum value of U_(c) among all the configuredserving cells, U_(c) is the total number of received PDSCHs andPDCCH/EPDCCH indicating downlink SPS release in subframe(s) n-k on thec-th serving cell, k∈K. The UE shall not transmit HARQ-ACK on PUSCH ifthe UE does not receive PDSCH or PDCCH/EPDCCH indicating downlink SPSrelease in subframe(s) n-k where k∈K and

W_(DAI) ^(UL)

=4.

In Reference 2, one UL DAI value may mean a plurality of DL subframes inassociation with the detected number of PDSCHs (e.g., U) because it isassumed that a possibility of failing to detect 4 or more consecutivePDSCHs is very low. However, in an unlicensed band CC, a PDSCH detectionfailure possibility may increase and thus a DL subframe group that canbe reliably distinguished by the UE may be different from a valueproposed in Reference 1. As an example, assuming that a possibility ofconsecutively failing to detect 5 PDSCHs even in the unlicensed band CCis low, a mapping relationship between a UL DAI and a DL subframe may beconfigured as indicated in [Math. 6].B _(c) ^(DL) =W _(DAI) ^(UL)+5|(U−W _(DAI) ^(UL))/5|  [Math. 6]

Additionally, the eNB may predetermine reference configuration regardingthe number of DL subframes corresponding to a UL DAI value and indicatewhether a specific UL DAI conforms to the reference configuration orindependent configuration for each CG according to the operation of thepresent invention by adding a bit field to DCI indicating a PUSCHresource. For example, one bit may be added to DCI to indicate whether aUL DAI applies the number of DL subframes according to the mappingrelationship of Reference 1 to all CGs or independently applies thenumber of DL subframes according to the mapping relationship of Table 8to each CG.

The operation of the present invention may also be extended to a DL DAI.That is, the eNB may independently configure, for the UE, the number ofDL subframes indicated by the DL DAI with respect to each CG orinterpretation of the DL DAI.

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs on aPUSCH resource by applying the UCI piggybacking scheme including theseparate UCI coding/resource mapping scheme for each CG, for example, byapplying separate coding for each CG or applying coding for all of theUCI without distinguishing between CGs, the eNB configures, for the UE,an offset value for a UL DAI value (or the number of DL subframesindicated by a UL DAI value) for each CG through a higher layer signaland informs the UE of an indicator indicating whether to apply the ULDAI offset value for each CG to the UCI piggybacking process of a PUSCHresource.

As a modified operation of the method for independently configuring thenumber of DL subframes corresponding to the UL DAI with respect to eachCG, the UL DAI offset value for each CG may be preconfigured todistinguish between interpretations of UL DAI offset values of CGs andthe eNB may transmit dynamic signaling indicating whether to apply theUL DAI offset value to the UE, thereby flexibly adjusting a UCI payloadsize.

DL Signaling

1. DL/UL DAI Across all CGs for Each CG (Hereinafter, “DL/UL DAI AcrossCCs for Each CC”) Transmission

According to a specific embodiment of the present invention, a method isproposed in which, when the UE transmits UCI for a plurality of CGs on aPUSCH resource by applying the UCI piggybacking scheme including theseparate UCI coding/resource mapping scheme for each CG, for example, byapplying separate coding for each CG or applying coding for all of theUCI without distinguishing between CGs, the eNB informs the UE of a DLDAI indicating the accumulated number of PDSCH transmissions within theCG up to a corresponding PDSCH transmission timing through DL controlsignaling (e.g., DCI) indicating specific PDSCH transmission within theCG. The DL DAI represents the accumulated number of all PDSCHstransmitted for all CCs in the CG and in all DL subframe durationsconfigured in the TDD system. Similarly, the eNB may inform the UE of aUL DAI indicating the accumulated number of PDSCHs commonly assumed bythe UE for all CGs (all CCs and all configured DL subframe durations areassumed) through DCI indicating PUSCH transmission. In this case, anorder of PDSCH transmissions indicated by the DL DAI in the CG may beassigned in a time-first manner. The number of PDSCHs transmitted in allCCs in the CG and in all DL subframe durations configured in the TDD maybe calculated by adding the number of DL subframes in which a PDSCH foreach CC is transmitted. An operation according to this scheme has anadvantage of reusing existing signaling by extending the concept of anexisting DAI.

However, in the LTE system according to an embodiment of the presentinvention, an additional UL/DL DAI field is not present in DCI in theFDD system and a DAI field of DCI format 0 in the TDD system is used toindicate a UL index for multiple UL subframe scheduling rather than fora UL DAI, in the case of UL-DL configuration #0. Accordingly, a DL/ULDAI for counting PDSCH transmission in a DL subframe duration and forCCs in the CG may be provided as one of the following two methods.

(i) Introduction of an additional bit field in DCI

(ii) (In the case of TDD UL-DL configuration #0) preconfiguration of aUL DAI value according to each state of a UL index

In this case, if the bit field is added in the DCI according to (i), theDCI including the added bit field should be defined only when the DCI istransmitted in a UE-specific search space (USS) because introduction ofthe additional bit field in DCI format 0 in a common search space (CSS)is not desirable when coexistence with the UE performing a legacyoperation in the CSS and a fallback operation in the CSS are considered.

The DL/UL DAI across CCs for each CG may be signaled only for specificCGs and may not be signaled for the other CGs. For example, the DL/ULDAI across CCs may not be signaled for a CG consisting only of an L-celland may be signaled for a CG including a U-cell.

2. DL DAI Signaling and Interpretation Method of UE DuringMulti-CC/Multi-Subframe Scheduling

2.1. Separate DL/DAI Configuration and Interpretation According toSingle/Multiple PDSCH Scheduling

According to a specific embodiment of the present invention, a method isproposed in which the UE independently interprets a value indicated by aDL DAI within each DCI type, when the eNB informs the UE of a DL DAIindicating the accumulated number of PDSCH transmissions up to acorresponding PDSCH transmission timing in DCI indicating specific PDSCHtransmission, DCI indicating single PDSCH scheduling is referred to asDCI type 1, and DCI indicating multiple PDSCH scheduling is referred toas DCI type 2. That is, a DL DAI in DCI type 1 means the accumulatednumber of PDSCH transmissions indicated by DCI type 1 and a DL DAI inDCI type 2 means the accumulated number of PDSCH transmissions (or thenumber of DL scheduling) indicated by DCI type 2. In this case, the UEmay distinguish between DCI types by the length of DCI or a radionetwork temporary identifier (RNTI) scrambled into a CRC bit of the DCI.

In an LTE Rel-8 system according to an embodiment of the presentinvention, multiple states for the number of subframes in which PDSCHsare transmitted are expressed in Reference 3 below by a DL DAI having abit field having 2 bits. For example, state ‘00’ of a DL DAI mayindicate that 1, 5, or 9 PDSCHs are accumulatively transmitted. Thereason why the accumulated number of PDSCH transmissions is representedby one state as described above is that a possibility that the UEconsecutively fails to detect plural (e.g., 4) PDCCH (or DCI)transmissions is expected to be very low.

[Reference 3]

TABLE 9 VUL, Number of subframes including PDCCH/ DAI MSB, DAI or EPDCCHindicating PDSCH transmission and LSB VDL, DAI DL SPS release 0, 0 1 1,5 or 9 0, 1 2 2, 6 or 10 1, 0 3 3 or 7 1, 1 4 0, 4 or 8

It is assumed that a DL/UL DAI represents the accumulated number ofPDSCH transmissions in the CC domain, DCI A in a specific DL subframeindicates multi-CC scheduling for 4 CCs (e.g., CC1, CC2, CC3, and CC4),and DCI B represents single CC scheduling for one CC (e.g., CC5),according to the DL/UL DAI across CCs for each CG

In this case, the eNB may allocate a PUSCH resource by DCI indicating aUL grant with respect to a UL subframe in which an ACK/NACK resource fora DL subframe is transmitted and the eNB may indicate ACK/NACKtransmission for 5 PUSCHs by a UL DAI value in the DCI. It is assumedthat the eNB informs the UE that 4 accumulative PDSCHs are transmittedby setting a DL DAI value in DCI A to ‘11’ and that 5 accumulativePDSCHs are transmitted by setting a DL DAI value in DCI B to ‘00’.

In this case, when the UE fails to detect DCI A and succeeds indetecting DCI B, if the DL DAI value ‘00’ in DCI B means transmission of1, 5, or 9 accumulative PDSCHs similar to existing design, the UE has adifficulty in determining whether the first PDSCH among 5 PDSCHs hasbeen successfully detected or the fifth PDSCH has been successfullydetected. The reason why it is difficult to determine detection is thatthe UE should consecutively fail to detect DCI four times in order tojudge ‘00’ as 5 accumulative PDSCHs in the case of single PDSCHscheduling and a possibility that such a case occurs is very low.However, when multiple PDSCH scheduling such as multi-CC scheduling isconsidered, a situation in which it is difficult for the UE to make adecision may occur even when the UE fails to detect DCI once asdescribed in the above example.

Accordingly, the present invention proposes a method in which the UEseparately interprets a DL DAI with respect to the case in which a DLDAI indicates single PDSCH scheduling (or DCI indicates single PDSCHscheduling) and the case in which the DL DAI indicates multiple PDSCHscheduling (or DCI indicates multiple PDSCH scheduling). As an example,the accumulated number of PDSCH transmissions indicated by the DL DAI inDCI indicating single PDSCH scheduling does not include PDSCHscorresponding to DCI indicating multiple PDSCH scheduling. Similarly,the accumulated number of PDSCH transmissions (or the number of DLscheduling) indicated by the DL DAI in DCI indicating multiple PDSCHscheduling does not include PDSCHs corresponding to DCI indicatingsingle PDSCH scheduling.

2.2. DL/UL DAI Application Method for Multiple PDSCH Scheduling

According to a specific embodiment of the present invention, a method isproposed in which the eNB semi-statically informs the UE of the numberof PDSCHs or the maximum number of PDSCHs which can be DL scheduled byone DCI and informs the UE of a DL DAI indicating the accumulated numberof DL scheduling (or the accumulated number of DCI) up to acorresponding DCI transmission timing in DCI indicating specific PDSCHtransmission. In this case, the accumulated number may be counted in aspecific CC group and during a specific DL subframe duration, scheduledbetween the eNB and the UE. Similarly, the eNB may inform the UE of a ULDAI indicating the accumulated number of DL scheduling (or theaccumulated number of DCI or the accumulated number of PDSCHs) to beassumed by the UE for HARQ-ACK response feedback in DCI indicating PUSCHtransmission. In this case, the accumulated number may be counted in aspecific CC group and during a specific DL subframe duration,prescheduled between the eNB and the UE. Meanwhile, the UE may calculatean entire HARQ-ACK payload by the number of DL scheduling indicated by aUL DAI and the maximum number of PDSCHs which can be transmitted in eachDL scheduling. For example, the entire HARQ-ACK payload size may beproportional to the product of the accumulated number of DL schedulingindicated by the UL DAI and the maximum number of PDSCHs which can beindicated by DL scheduling. In this case, DL scheduling represents anoperation in which the eNB indicates PDSCH transmission through DLcontrol signaling (e.g., DCI).

Even in the case of multiple PDSCH scheduling, if a DL subframe in whichcorresponding DCI is transmitted is preconfigured and the number ofPDSCHs supported by multiple PDSCH scheduling is semi-staticallyconfigured, a DL DAI and a UL DAI may be effectively applied. As anexample, it is assumed that the UE feeds back HARQ-ACK for PDSCHs thatcorresponding DCI schedules with respect to a DL subframe in which DCIfor multiple PDSCH scheduling is transmitted to the eNB in a specificsingle UL subframe. It is also assumed that the eNB sets the number ofPDSCHs supported by multiple PDSCH scheduling to M.

Then, the eNB may inform the UE of a DL DAI indicating the number of DLscheduling (or the number of DCI indicating plural PDSCH transmissions)(for multiple PDSCHs) accumulated up to corresponding DCI transmissionin DCI indicating plural PDSCH transmissions or inform the UE of a ULDAI indicating the accumulated number of DL scheduling assumed by the UE(for multiple PDSCHs), the accumulated number of PDSCHs, or theaccumulated number of DCI indicating a plurality of PDSCHs, in DCIindicating PUSCH transmission. The UE may then calculate an entireHARQ-ACK payload by the accumulated number of DCI indicated by the ULDAI and the number of PDSCHs (e.g., M) of multiple PDSCH scheduling,confirms which DL scheduling is omitted through the DL DAI, and whenomitted DL scheduling is detected, report NACK for the M PDSCHs.

That is, an operation may be performed in the form of increasing only anACK/NACK payload size for each DL scheduling from a legacy operation ofa DL DAI and a UL DAI.

2.3. Separate Coding and Separate UCI Resource Allocation MethodAccording to Single/Multiple PDSCH Scheduling

According to a specific embodiment of the present invention, a method isproposed in which, when the UE piggybacks UCI on a PUSCH resource beingtransmitted, channel coding is applied by distinguishing betweenHARQ-ACK information for single PDSCH scheduling and HARQ-ACKinformation for multiple PDSCH scheduling and coded symbols of the twodistinguished groups (i.e., a coded symbol for single PDSCH schedulingand a coded symbol for multiple PDSCH scheduling) are allocated todistinguishable UCI resources.

If HARQ-ACK for multiple PDSCH scheduling is excluded from a HARQ-ACKtransmission process for single PDSCH scheduling, the HARQ-ACKtransmission process for single PDSCH scheduling has an advantage ofapplying a method of a legacy LTE system except for additionallydetermining single or multiple PDSCH scheduling.

In this case, if the form of multiple PDSCH scheduling is multi-CCscheduling, DCI for single CC scheduling and DCI for multi-CC schedulingmay coexist in a specific DL subframe. In addition, if HARQ-ACK for aPDSCH transmitted in the DL subframe is transmitted through a UCIpiggybacking process in a PUSCH resource in a specific single ULsubframe, a UL DAI may be interpreted as the number of DL scheduling inthe case of multi-CC scheduling unlike a conventional scheme and thusHARQ-ACK for multi-CC scheduling is desirably transmitted separatelyfrom HARQ-ACK for single-CC scheduling.

In this case, a UL DAI for single PDSCH scheduling and a UL DAI formultiple PDSCH scheduling may have distinguishable bit fields.

UCI Adaptation Method in Case of UCI on PUSCH Over CG

“UCI on PUSCH over CG” refers to an operation in which the UE piggybacksUCI for CCs belonging to different CGs on a single PUSCH resource.

PUCCH Reference CG Based Separate/Joint UCI Coding

According to a specific embodiment of the present invention, a method isproposed for applying separate UCI coding and separate RE mapping (for acoded UCI symbol) or applying joint coding and corresponding RE mappingfor a plurality of PUCCH CGs, in units of a group of CCs in which cellsfor PUCCH transmission are identically configured (hereinafter, a PUCCHCG) as described below, when the UE can piggyback UCI for CCs belongingto different CGs on a single PUSCH resource (i.e. an operation of UCI onPUSCH over CG can be performed).

(1) Application of separate UCI coding and separate RE mapping (for acoded UCI symbol) to each of plural CGs: In this case, the plural CGsmay be CGs randomly configured in a single PUCCH situation or CGsassociated or configured with PUCCHs in a dual PUCCH situation.

(2) Application of joint UCI coding and corresponding RE mapping to allof plural CGs: In this case, the plural CGs may be CGsassociated/configured with respect to each PUCCH in a dual PUCCHsituation.

While the separate UCI coding and separate RE mapping method for each CGwhich can be randomly configured has been proposed hereinabove, the“PUCCH reference CG based separate/joint UCI coding” operation providesseparate UCI coding and separate RE mapping in units of PUCCH CGs. Inthis case, when the UE performs UCI piggybacking in a PUSCH resource,the UE may piggyback UCI for a CG in which scheduling is present on acorresponding CG with respect to each PUCCH CG and may not piggyback UCIfor a CG on which scheduling is not present. “PUCCH reference CG basedseparate/joint UCI coding” includes a method for maximizing coding gainby applying joint UCI coding to a plurality of PUCCH CGs when joint UCIcoding is applied.

When separate coding per PUCCH CG in (1) is applied, an RE mapping orderfor a coded UCI symbol may conform to an index order of the PUCCH CG.Alternatively, in the case of dual PUCCHs, RE mapping for a PUCCH CGincluding a primary cell (hereinafter, PCG) may first be performed andRE mapping for a PUCCH CG which does not include a primary cell(hereinafter, an SCG) may subsequently be performed. The primary cellrefers to a cell in charge of RRC connection in a CA environment.

When joint coding is applied to all PUCCH CGs in (2), an input order ofa channel coder (e.g., RM coder) may be determined according to a cellindex (or a CC index) as in the CA environment or UCI for a PCG may befirst input and UCI for an SCG may subsequently be input. In this case,an order of UCI input to each PUCCH CG may conform to a cell index (or aCC index).

A/N Spatial Bundling

According to a specific embodiment of the present invention, a method isproposed for determining whether to apply spatial bundling for HARQ-ACK(hereinafter, A/N spatial bundling) corresponding to CG according to acombination of a duplexing scheme of a PUCCH cell for each PUCCH CG anda PUCCH transmission type (e.g., PUCCH format 3 (hereinafter, PF3) orchannel selection (hereinafter, CHsel), when a HARQ-ACK payload size ofCCs in all PUCCH CGs is greater than specific B bits (e.g., 20 bits) inthe case in which the UE piggybacks UCI for a plurality of PUCCH CGs(i.e., a group of CCs in which cells for PUCCH transmission areidentically configured) on a single PUSCH resource. Herein, A/N spatialbundling means applying AND operation after calculating a HARQ-ACK bit(e.g., a bit indicating ACK or NACK) for each TB when two or more TBsare transmitted. For example, in the case of {ACK (=‘1’), NACK (=‘0’)},NACK (=‘1’ & ‘0’=‘0’) is derived as a result of spatial bundling.

(1) Option 1: Uniformly apply spatial bundling to A/N of all CGs

(2) Option 2: Determine whether to apply A/N spatial bundling for eachCG according to a combination of a duplexing scheme of a PUCCH cell anda PUCCH format

[Example] the Case in which a Maximum of 5 Cells (or CCs) is Included inEach PUCCH CG, Two PUCCH Cells are Present, and B=20 Bits

TABLE 10 PUCCH CG PUCCH CG including PUCCH including PUCCH PUCCH Cell 1PUCCH Cell 2 cell 1 cell 2 TDD PF3 FDD PF3 A/N spatial — bundling TDDPF3 FDD PF3 A/N spatial A/N spatial bundling bundling TDD PF3 FDD CHselA/N spatial — bundling TDD CHsel FDD PF3 — — TDD CHsel FDD CHsel — —

In this case, whether a HARQ-ACK payload size exceeds B bits isdetermined based on a HARQ-ACK payload size for all PUCCH CGs when jointcoding is applied to all PUCCH CGs and on a HARQ-ACK payload size foreach CG when separate coding is applied to each PUCCH CG.

Alternatively, a method for determining whether to apply A/N spatialbundling to each CG may be defined as follows.

(1) If a HARQ-ACK payload size for all PUCCH CGs exceeds B bits, A/Nspatial bundling for each PUCCH CG is performed according to thefollowing priority until the HARQ-ACK payload size is less than the Bbits.

A. PUCCH CG (including a TDD PF3 PUCCH cell)>PUCCH CG (including TDDCHsel)>PUCCH CG (including an FDD PF3 PUCCH cell)>PUCCH CG (includingFDD CHsel)

B. If two PUCCH CGs have the same duplexing scheme of PUCCH cells andthe same PUCCH transmission type, A/N spatial bundling may first beperformed with respect to an SCG or A/N spatial bundling may beperformed according to a CG index.

Similarly, even in the above case, whether a HARQ-ACK payload sizeexceeds the B bits is determined based on a HARQ-ACK payload size forall PUCCH CGs when joint coding is applied to all PUCCH CGs and on aHARQ-ACK payload size for each CG when separate coding is applied toeach PUCCH CG.

As an additional operation of the present invention, if there is aplurality of available PUSCH resources, the UE may transmit only UCIcorresponding to one CG to each PUSCH for piggybacking and, if only oneavailable PUSCH resource is present, the UE may transmit UCIcorresponding to all CGs to a corresponding PUSCH for piggybacking. Inthe latter case, separate coding and separate RE mapping may be appliedto each of the CGs and, in the former case, separate coding and separateRE mapping may be applied only to HARQ-ACK feedback (CSI feedback ispiggybacked on one specific PUSCH resource) or only to HARQ-ACK feedbackand RI/PTI feedback (the other CSI feedback (e.g., CQI/PMI) ispiggybacked on one specific PUSCH resource). FIG. 22 illustrates anexample of the above operation of transmitting UCI on a subset basiswhen a plurality of available PUSCH resources is present.

As an additional operation of the present invention, the followingproposals may be applied, when a CC domain DAI indicating orderinformation of scheduled CCs is present, the CC domain DAI is definedfor each CG (i.e., C-DAI₁ and C-DAI₂) with respect to CG₁ consistingonly of CCs configured to transmit one TB and CG₂ consisting only of CCsconfigured to transmit up to 2 TBs, and the CC domain DAI is transmittedin DCI for a PDSCH transmitted in a corresponding CG (i.e., the CCdomain DAI is independently applied/signaled with respect to each CG).

[Proposed Method A-1] A total DAI (hereinafter, T-DAI) indicating thetotal number of CCs scheduled for all CCs included in CG₁ and CG₂ isdefined separately from the CC domain DAI and both the T-DAI and the CCdomain DAI are transmitted through DL scheduling grant DCI.

For example, it is assumed that CG₁ consists of CC₁, CC₂, CC₃, CC₄, andCC₅ and CG₂ consists of CC₆, CC₇, CC₈, CC₉, and CC₁₀. If an eNBschedules CC₁, CC₃, CC₄, CC₇, CC₈ and CC₉, then C-DAI₁ values for CC₁,CC₃ and CC₄ may indicate 1, 2, and 3, respectively, and C-DAI₂ valuesfor CC₇, CC₈, and CC₉ may indicate 1, 2, and 3, respectively. In thiscase, if the UE fails to detect DCI for all PDSCHs transmitted in CG₁,the eNB expects a UCI (e.g., A/N) payload of 9 (=3×1+2×3) bits but theUE configures a UCI (e.g., A/N) payload of 6 (=2×3) bits, therebyresulting in inconsistency between the eNB and the UE. To eliminate suchinconsistency, the present invention proposes a method for including aT-DAI indicating the total number of scheduled CCs, as an indicator foran entire UCI (e.g., A/N) payload, in DCI corresponding to all PDSCHstransmitted in CG₁ or CG₂. For example, in the above example, the T-DAIvalue may be indicated as 6 and the cNB and UE may schedule a value(e.g., 6×2=12) corresponding to a product of a value (e.g., 6) indicatedby the T-DAI and the total number (e.g., 2) of TBs configured to betransmitted in an arbitrary CC as a UCI (e.g., A/N) payload.

[Proposed Method A-2] The eNB configures a specific PUCCH format (or amaximum UCI payload preconfigured by the eNB) having a maximum payloadsize of N₁ bits and the UE calculates a product N₂ of the total numberof CCs indicated by the T-DAI received in Proposed Method A-1 and themaximum number (e.g., 2) of TBs configured to be transmitted in anarbitrary CC and sets a UCI payload size (e.g., an A/N payload size), N,to N=min(N₁, N₂) bits.

Using the T-DAI defined in Proposed Method A-1 of the present invention,the eNB and the UE may schedule a UCI (e.g., A/N) payload therebetween.For example, the eNB and the UE may schedule a value (e.g., N2)corresponding to a product of a value indicated by the T-DAI and themaximum number of TBs as a UCI (e.g., A/N) payload. However, if the eNBpreallocates a PUCCH format having a maximum UCI (A/N) payload of N₁bits, the UE desirably configures a UCI (e.g., A/N) payload as N₂ bitswhen N₂ is less than N₁ and as N₁ bits when N₂ is greater than N₁. Thatis, the UCI payload may be set to min(N₁, N₂) bits.

[Proposed Method A-3] With respect to N bits (or N₁=N bits areconsidered without additional T-DAI signaling) configured in ProposedMethod A-2, the UE fills UCI (e.g., A/N) for CG₁ (a CG consisting of CCshaving one TB) according to an index order of C-DAI₁ starting from aleast significant bit (LSB) (or a most significant bit (MSB)) of a UCIpayload (i.e., so as to map a high (or low) UCI bit index to C-DAI₁ of alow index) and fills UCI (e.g., A/N) for CG₂ (a CG consisting of CCshaving two TBs) according to an index order of C-DAI₂ starting from anMSB (or an LSB) (i.e., so as to map a low (or high) UCI bit index toC-DAI₂ of a low index).

According to Proposed Methods A-2 and A-3, if DCI for the last-orderedscheduled CC of each CG is omitted even when a UCI payload isconfigured, the UE is unable to know in which order UCI (e.g., A/N) forCCs is filled. For example, in Proposed Method A-1, it may be assumedthat UCI (e.g., A/N) for CCs scheduled in CG₁ is filled in order of alow index of C-DAI₁ and UCI (e.g., A/N) for CCs scheduled in CG₂ isfilled in order of a low index of C-DAI₂ in a state in which the UEfails to detect DCI for CC₄ and CC₉. In this case, while the eNB expects3 UCI (e.g., A/N) for 1 TB and 3 UCI (e.g., A/N) for 2 TBs, the UEtransmits 2 UCI (e.g., A/N) for 1 TB and 2 UCI (e.g., A/N) for 2 TBs,thereby resulting in inconsistency between the eNB and the UE.Accordingly, the present invention proposes a method for reducinginconsistency between the eNB and the UE by filling UCI (e.g., A/N) forCG₁ (a CG consisting of CCs having one TB) according to an index orderof C-DAI₁ starting from an LSB (or an MSB) and filling UCI (e.g., A/N)for CG₂ (a CG consisting of CCs having two TBs) according to an indexorder of C-DAI₂ starting from an MSB (or an LSB), when a UCI (e.g., A/N)of N bits is configured in Proposed Method A-2.

As a specific example, assuming that a bit stream obtained by numeratingbits in a UCI payload starting from an MSB is b₀, b₁, . . . , b_(N-1),1-bit UCI corresponding to C-DAI₁=1, 2, 3 may be sequentiallyarranged/mapped to bits b_(N-1), b_(N-2), and b_(N-3), respectively and2-bit UCI corresponding to C-DAI₂=1, 2, 3 may be sequentiallyarranged/mapped to bits (b₀, b₁), (b₂, b₃), (b₄, b₅), respectively.

As an additional operation of the present invention, the followingmethods are proposed when order information (or counting information) ofscheduled CCs is present, a CC domain DAI for each CG is defined withrespect to CG₁ and CG₂ (i.e., C-DAI₁ and C-DAI₂), and the CC domain DAIis transmitted in DCI for a PDSCH transmitted in a corresponding CG(i.e., the CC domain DAI is independently applied/signaled to each CG).

[Proposed Method B-1] A method is proposed for applying and signalingall DAIs indicating the total number of TBs scheduled in a plurality ofCGs when a counter DAI for each CG, indicating the number of CCsscheduled for CG with respect to each of the CGs is applied andsignaled.

For example, when CC domain DAIs are defined (i.e., C-DAI₁ and C-DAI₂)for each CG with respect to CG₁ consisting of CCs configured to transmitone TB and CG₂ consisting of CCs configured to transmit two TBs andtransmitted in DCI for a PDSCH transmitted in a corresponding CG, it isassumed that CG₁ consists of CC₁, CC₂, CC₃, CC₄, and CC₅ and CG₂consists of CC₆, CC₇, CC₈, CC₉, and CC₁₀. If the eNB schedules CC₁, CC₃,CC₄, CC₇, CC₈, and CC₉, values of C-DAI₁ for CC₁, CC₃, and CC₄ mayindicate 1, 2, and 3, respectively and values of C-DAI₂ for CC₇, CC₈,and CC₉ may indicate 1, 2, and 3, respectively. Next, it may be assumedthat the UE has not received DCI only for CC₉ among scheduled CCs. If aT-DAI indicating the total number of scheduled CCs is applied andsignaled as indicated in A-1 of the present invention, the UE isinformed that 6 cells have been scheduled, through the T-DAI and, inthis case, the UE may recognize that DCI for one cell has been missedbut cannot be aware of whether a fourth-scheduled CC has been presentand the UE has missed a fourth-scheduled CC from CG₁ or whether the UEhas missed a third-scheduled CC (i.e., CC₉) from CG₂, thereby generatinga situation in which payload calculation is not clear. Therefore, thepresent invention proposes a method for applying and signaling a T-DAIindicating the total number of TBs scheduled in a plurality of CGs. Inthe above example, if the T-DAI indicates the total number of TBs as 9(=1×3+2×3), the UE may judge that scheduling for two TBs has beenmissed. As a specific example, when it is assumed that a possibility ofconsecutively missing 4 consecutive cells is low, a 2-bit counter DAI ofa cell level may be applied to each of a 1-TB CG and a 2-TB CG and atotal 3-bit DAI of a TB level may be applied to the two CGs.

[Proposed Method B-2] A method is proposed for defining a total DAI 1(hereinafter, T-DAI₁) indicating the total number of CCs (or TBs)scheduled among CCs in CG₁ to transmit T-DAI₂ in DL scheduling grant DCIfor CG₁ and defining a total DAI 2 (hereinafter, T-DAI₂) indicating thetotal number of CCs (or TBs) scheduled among CCs in CG₂ to transmitT-DAI₂ in a DL scheduling grant DCI for CG₂ when a counter DAI for eachCG (i.e., C-DAI₁ and C-DAI₂), indicating the number of scheduled CCs foreach CG with respect to two CGs (i.e., CG₁ and CG₂) is applied andsignaled and for feeding back UCI using PUCCH resource 1 when the UEdetermines that scheduling only for CG₁ or CG₂ is present and usingPUCCH resource 2 when the UE determines that scheduling for CG₁ and CG₂is present.

If the number of scheduled CCs in each CG is indicated by a total DAIfor each CG as described above, the eNB and the UE may calculatedifferent payloads in the case of missing all of DCI for a specific CG.Accordingly, the present invention proposes a method in which the UEperforms UCI feedback by selecting a PUCCH resource according to acombination of scheduled CGs determined thereby so that the eNB mayjudge a DCI missing problem in a specific CG through BD. Morespecifically, when two CCs, CG₁ and CG₂ are present, the eNB mayconfigure different PUCCH resources (e.g., PUCCH₁, PUCCH₂, and PUCCH₃)with respect to a combination of 3 scheduled CGs {CG₁}, {CG₂}, and {CG₁,CG₂} and the UE may feed back UCI to a PUCCH corresponding to thecombination of scheduled CGs according to a DCI detection result.

[Proposed Method B-3] A method is proposed for defining a total DAI(hereinafter, T-DAI_(ALL)) indicating the total number of CCs (or TBs)scheduled among CCs in CG₁ and CG₂ (i.e., CCs in a union of CG₁ and CG₂)to transmit T-DAI_(ALL) in DL scheduling grant DCI for CG₁ and defininga total DAI 2 (hereinafter, T-DAI₂) indicating the total number of CCs(or TBs) scheduled among CCs in CG₂ to transmit T-DAI₂ in DL schedulinggrant DCI for CG₂, when a counter DAI for each CG (i.e., C-DAI₁ andC-DAI₂) indicating the number of scheduled CCs in each CG is applied andsignaled with respect to two CGs (i.e., CG₁ and CG₂).

When two CGs, CG₁ and CG₂, are defined and the number of CCs scheduledin each CG is indicated as total DAIs (e.g., T-DAI₁ and T-DAI₂) for eachCG, if the eNB performs scheduling for some CCs in CG₁ and some CCs inCG₂, the UE may recognize a scheduling situation as the following threecases.

(1) The UE may determine that scheduling only for CG₁ is present andcalculate an A/N payload as T-DAI₁.

(2) The UE may determine that scheduling for CG₂ is present andcalculate an A/N payload as T-DAI₂.

(3) The UE may determine that scheduling for both CG₁ and CG₂ is presentand calculate A/N payloads as T-DAI₁ and T-DAI₂.

In this case, the eNB should be aware of which assumptions are made whenthe UE configures an A/N payload (or a UCI payload) by performing BD forthe above three situations. However, if A/N payloads (or UCI payloads)for CG₁ and CG₂ have the same value, the eNB cannot determine for whichCG the UE has transmitted A/N (or UCI). Accordingly, the presentinvention proposes a method for applying and signaling T-DAIALLindicating the total number of CCs (or TBs) scheduled in two CGs withrespect to one (e.g., CG₁) of two CGs (e.g., CG₁ and CG₂) and applyingand signaling T-DAI₂ indicating the total number of CCs (or TBs)scheduled in a corresponding CG with respect to the other CG (e.g.,CG₂). In this case, a mapping order of an A/N payload (or UCI payload)may conform to an order of CG₁>CG₂. That is, A/N (or UCI) for a CG towhich T-DAI_(ALL) is applied is allocated first. According to anoperation of the present invention, the UE in the above example mayrecognize a scheduling situation again as the following two cases.

(1) The UE determines that scheduling for at least CG₁ is present andcalculates an A/N payload as T-DAI_(ALL).

(2) The UE determines that scheduling only for CG₂ is present andcalculates an A/N payload as T-DAI₂.

In this case, since T-DAI_(ALL) will always have a value greater thanT-DAI₂, the eNB may distinguish between T-DAI_(ALL) and T-DAI₂ by a UCIpayload size.

[Proposed Method B-4] A method is proposed in which, when a counter DAI(i.e., C-DAI₁ and C-DAI₂) for each CG, indicating the number of CCsscheduled in each CG with respect to two CGs (i.e., CG₁ and CG₂) isapplied and signaled, a total DAI 1 (hereinafter, T-DAI₁) indicating thetotal number of CCs (or TBs) scheduled among CCs in CG₁ is defined totransmit T-DAI₁ in DL scheduling grant DCI for CG₁, a total DAI 2(hereinafter, T-DAI₁) indicating the total number of CCs (or TBs)scheduled among CCs in CG₂ is defined to transmit T-DAI₂ in DLscheduling grant DCI for CG₂, and the UE indicates for which CGcombination feedback has been performed by adding M bits during UCI (orA/N) feedback.

For example, the UE may add 2 bits in a process of configuring an A/Npayload to indicate that A/N only for CG1 is present in the case of‘01’, that A/N only for CG₂ is present in the case of ‘10’, and that A/Nfor CG₁ and CG₂ is present in the case of ‘11’. Then, the eNB maydetermine which assumption the UE has made for the three schedulingsituations described in Proposed Method B-3. Alternatively, the UE mayuse one bit to indicate only whether A/N for a specific CG (e.g., CG₂)is included. In this case, the UE may distinguish between the case inwhich A/N only for CG₂ is fed back and the case in which A/N for CG₁ andCG₂ is fed back by BD.

When Proposed Methods B-1, B-2, B-3, and B-4 are applied, a mappingorder on an A/N payload may conform to Proposed Method A-3.

FIG. 23 is a block diagram of a transmitting device 10 and a receivingdevice 20 configured to implement exemplary embodiments of the presentinvention. Referring to FIG. 23 , the transmitting device 10 and thereceiving device 20 respectively include radio frequency (RF) units 13and 23 for transmitting and receiving radio signals carryinginformation, data, signals, and/or messages, memories 12 and 22 forstoring information related to communication in a wireless communicationsystem, and processors 11 and 21 connected operationally to the RF units13 and 23 and the memories 12 and 22 and configured to control thememories 12 and 22 and/or the RF units 13 and 23 so as to perform atleast one of the above-described embodiments of the present invention.

The memories 12 and 22 may store programs for processing and control ofthe processors 11 and 21 and may temporarily storing input/outputinformation. The memories 12 and 22 may be used as buffers. Theprocessors 11 and 21 control the overall operation of various modules inthe transmitting device 10 or the receiving device 20. The processors 11and 21 may perform various control functions to implement the presentinvention. The processors 11 and 21 may be controllers,microcontrollers, microprocessors, or microcomputers. The processors 11and 21 may be implemented by hardware, firmware, software, or acombination thereof. In a hardware configuration, Application SpecificIntegrated Circuits (ASICs), Digital Signal Processors (DSPs), DigitalSignal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), orField Programmable Gate Arrays (FPGAs) may be included in the processors11 and 21. If the present invention is implemented using firmware orsoftware, firmware or software may be configured to include modules,procedures, functions, etc. performing the functions or operations ofthe present invention. Firmware or software configured to perform thepresent invention may be included in the processors 11 and 21 or storedin the memories 12 and 22 so as to be driven by the processors 11 and21.

The processor 11 of the transmitting device 10 is scheduled from theprocessor 11 or a scheduler connected to the processor 11 and codes andmodulates signals and/or data to be transmitted to the outside. Thecoded and modulated signals and/or data are transmitted to the RF unit13. For example, the processor 11 converts a data stream to betransmitted into K layers through demultiplexing, channel coding,scrambling and modulation. The coded data stream is also referred to asa codeword and is equivalent to a transport block which is a data blockprovided by a MAC layer. One transport block (TB) is coded into onecodeword and each codeword is transmitted to the receiving device in theform of one or more layers. For frequency up-conversion, the RF unit 13may include an oscillator. The RF unit 13 may include Nt (where Nt is apositive integer) transmit antennas.

A signal processing process of the receiving device 20 is the reverse ofthe signal processing process of the transmitting device 10. Under thecontrol of the processor 21, the RF unit 23 of the receiving device 10receives RF signals transmitted by the transmitting device 10. The RFunit 23 may include Nr receive antennas and frequency down-converts eachsignal received through receive antennas into a baseband signal. The RFunit 23 may include an oscillator for frequency down-conversion. Theprocessor 21 decodes and demodulates the radio signals received throughthe receive antennas and restores data that the transmitting device 10wishes to transmit.

The RF units 13 and 23 include one or more antennas. An antenna performsa function of transmitting signals processed by the RF units 13 and 23to the exterior or receiving radio signals from the exterior to transferthe radio signals to the RF units 13 and 23. The antenna may also becalled an antenna port. Each antenna may correspond to one physicalantenna or may be configured by a combination of more than one physicalantenna element. A signal transmitted through each antenna cannot bedecomposed by the receiving device 20. A reference signal (RS)transmitted through an antenna defines the corresponding antenna viewedfrom the receiving device 20 and enables the receiving device 20 toperform channel estimation for the antenna, irrespective of whether achannel is a single RF channel from one physical antenna or a compositechannel from a plurality of physical antenna elements including theantenna. That is, an antenna is defined such that a channel transmittinga symbol on the antenna may be derived from the channel transmittinganother symbol on the same antenna. An RF unit supporting a MIMOfunction of transmitting and receiving data using a plurality ofantennas may be connected to two or more antennas.

In embodiments of the present invention, a UE serves as the transmissiondevice 10 on uplink and as the receiving device 20 on downlink. Inembodiments of the present invention, an eNB serves as the receivingdevice 20 on uplink and as the transmission device 10 on downlink.

The transmitting device and/or the receiving device may be configured asa combination of one or more embodiments of the present invention.

The detailed description of the exemplary embodiments of the presentinvention has been given to enable those skilled in the art to implementand practice the invention. Although the invention has been describedwith reference to the exemplary embodiments, those skilled in the artwill appreciate that various modifications and variations can be made inthe present invention without departing from the spirit or scope of theinvention described in the appended claims. For example, those skilledin the art may use each construction described in the above embodimentsin combination with each other. Accordingly, the invention should not belimited to the specific embodiments described herein, but should beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

INDUSTRIAL APPLICABILITY

The present invention may be used for a wireless communication apparatussuch as a terminal, a relay and a base station (BS).

What is claimed is:
 1. A method for transmitting control information bya user equipment (UE) in a wireless communication system, the methodcomprising: receiving one or more physical downlink control channels(PDCCHs) each carrying downlink control information (DCI) including adownlink assignment index (DAI) related to downlink (DL) scheduling;performing, in one or more serving cells, a reception of each downlinkdata related to each of the one or more PDCCHs; and transmitting anacknowledgement/negative acknowledgement (ACK/NACK) response for thereception of each downlink data, wherein a value of the DAI denotes anaccumulated number that is counted for each pair of {each serving cellrelated to each downlink data, each PDCCH monitoring timing related toeach DL scheduling}.
 2. The method of claim 1, wherein the value of theDAI denotes the accumulated number that is counted, up to a currentPDCCH monitoring timing where a corresponding PDCCH is present.
 3. Themethod of claim 2, further comprising: receiving second DCI forscheduling a physical uplink shared channel (PUSCH), wherein theACK/NACK response is transmitted through the PUSCH scheduled by thesecond DCI, and the ACK/NACK response is generated based on a second DAIincluded in the second DCI.
 4. The method of claim 1, wherein a maximumnumber of serving cells supported by the UE is greater than
 5. 5. Themethod of claim 1, wherein the control information is generated based ona semi-statically configured maximum number of downlink data which canbe scheduled by each DCI for DL scheduling.
 6. A non-transitory computerreadable medium storing a program for performing the method of claim 1.7. A device for wireless communication, the device comprising: a memoryconfigured to store instructions; and a processor configured to performoperations by executing the instructions, the operations comprising:receiving one or more physical downlink control channels (PDCCHs) eachcarrying downlink control information (DCI) including a downlinkassignment index (DAI) related to downlink (DL) scheduling; performing,in one or more serving cells, a reception of each downlink data relatedto each of the one or more PDCCHs; and transmitting anacknowledgement/negative acknowledgement (ACK/NACK) response for thereception of each downlink data, wherein a value of the DAI denotes anaccumulated number that is counted for each pair of {each serving cellrelated to each downlink data, each PDCCH monitoring timing related toeach DL scheduling}.
 8. The device of claim 7, further comprising: atransceiver and wherein the device is a user equipment (UE) configuredto operate in a wireless communication system.
 9. The device of claim 7,wherein the device is an application specific integrated circuit (ASIC)or a digital signal processing device configured to control a userequipment (UE) in a wireless communication system.
 10. A method forreceiving control information by a base station (BS) in a wirelesscommunication system, the method comprising: transmitting one or morephysical downlink control channels (PDCCHs) each carrying downlinkcontrol information (DCI) including a downlink assignment index (DAI)related to downlink (DL) scheduling; performing, in one or more servingcells, a transmission of each downlink data related to each of the oneor more PDCCHs; and receiving an acknowledgement/negativeacknowledgement (ACK/NACK) response for the transmission of eachdownlink data, wherein a value of the DAI denotes an accumulated numberthat is counted for each pair of {each serving cell related to eachdownlink data, each PDCCH transmission timing related to each DLscheduling}.
 11. The method of claim 10, wherein the value of the DAIdenotes the accumulated number that is counted, up to a current PDCCHtransmission timing where a corresponding PDCCH is present.
 12. Themethod of claim 11, further comprising: transmitting second DCI forscheduling a physical uplink shared channel (PUSCH), wherein theACK/NACK response is received through the PUSCH scheduled by the secondDCI, and the ACK/NACK response is obtained based on a second DAIincluded in the second DCI.
 13. The method of claim 10, wherein amaximum number of serving cells supported by the BS is greater than 5.14. The method of claim 10, wherein the control information is obtainedbased on a semi-statically configured maximum number of downlink datawhich can be scheduled by each DCI for DL scheduling.
 15. Anon-transitory computer readable medium storing a program for performingthe method of claim
 10. 16. A device for wireless communication, thedevice comprising: a memory configured to store instructions; and aprocessor configured to perform operations by executing theinstructions, the operations comprising: transmitting one or morephysical downlink control channels (PDCCHs) each carrying downlinkcontrol information (DCI) including a downlink assignment index (DAI)related to downlink (DL) scheduling; performing, in one or more servingcells, a transmission of each downlink data related to each of the oneor more PDCCHs; and receiving an acknowledgement/negativeacknowledgement (ACK/NACK) response for the transmission of eachdownlink data, wherein a value of the DAI denotes an accumulated numberthat is counted for each pair of {each serving cell related to eachdownlink data, each PDCCH transmission timing related to each DLscheduling}.
 17. The device of claim 16, further comprising: atransceiver and wherein the device is a base station (BS) configured tooperate in a wireless communication system.
 18. The device of claim 16,wherein the device is an application specific integrated circuit (ASIC)or a digital signal processing device configured to control a basestation (BS) in a wireless communication system.